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Question 972558: how do you simplify radical 8x squared
Answer by ikleyn(53937)

You can put this solution on YOUR website!
.
how do you simplify radical 8x squared
~~~~~~~~~~~~~~~~~~~~~~~~

@lwsshak3 gives the answer in his post 2x%2Asqrt%282%29

.

This answer is incorrect, and I will explain it below.

In expression sqrt%288x%5E2%29

, value of x can be positive or negative (or zero).

Expression sqrt%288x%5E2%29

makes sense and is defined for both positive and/or negative values of x.

Also, according to the common agreement, square root of a number is understood in a middle school as a positive value.

THEREFORE, the correct answer to the problem's question is 2%2Aabs%28x%29%2Asqrt%282%29

.

It works universally for positive and negative values of 'x',
while expression 2x%2Asqrt%282%29

gives a negative value for negative 'x', which contradicts to the common agreement.

This question/problem is a standard highlight%28highlight%28TRAP%29%29

, and almost all
unfortunate newcomers, who are not familiar with this explanation, fall into this trap.

The percentage of these unfortunate newcomers is about 99.999%, I think, or even more than that.

Question 163137: Hi, this is the problem I was told to do:
[SQRT(2x + 2)] - [SQRT(x - 3)] = 2
or
√(2x+2) - √(x-3) = 2
I've been told to FOIL this problem, but I don't understand how to FOIL it if its subtracting and not multiplying. What I do know is that the answer is equal to 7.
Thanks in advance.
Answer by MathTherapy(10858)

(Show Source):

You can put this solution on YOUR website!

Hi, this is the problem I was told to do:

[SQRT(2x + 2)] - [SQRT(x - 3)] = 2
or
√(2x+2) - √(x-3) = 2

I've been told to FOIL this problem, but I don't understand how to FOIL it if its subtracting and not
multiplying. What I do know is that the answer is equal to 7.
Thanks in advance.
*****************
      
This might be easier and less confusing if one of the radicals is moved to the right side. So, let's choose  to do that with. 
                     ----- Adding   to both sides
                -- Squaring both sides
                
                         ---- FOILing right-side
                        
                        
             
                          
                       ---- Squaring both sides
                 
                 

            
                     
                          x - 7 = 0___x = 7

             You can do the CHECK!!

Question 720317: Here is my problem.
[SQRT(x + 7)] - 2[SQRT(x)] =-2
OR
√(x + 7) - 2√(x) = -2
-------
Now, the steps I took to solve this problem are to first square both sides:
[√(x + 7) - 2√(x)] * [√(x + 7) - 2√(x)] = 4
so then I FOIL the left side, resulting in:
(x+7) - [√(x + 7) * - 2√(x)] - [ - 2√(x) * √(x + 7)] + 4x
So then I thought to subtract (x+7) and (4x) to both sides
- [√(x + 7) * - 2√(x)] - [ - 2√(x) * √(x + 7)] = 4 - 4x - x - 7 (I think I'm supposed to switch the sign, because I've subtracted it and moved it to the opposite side, right?)
I think I'm correct up to this point, but now I have to square both sides again.
I think this left hand side could be re-written as:
-2[√(x + 7) * - 2√(x)]
Is this right? I'm subtracting it from itself, a negative, which could simply multiplied by -2. Anyway, now I need to square this again, so I assume the -2 becomes a 4 and I FOIL them separately?
FOILING the left side will get:
[√(x + 7) * - 2√(x)] * [√(x + 7) * - 2√(x)]
Which, when FOILed, looks like
(x+7) - [√(x+7) * -2√(x)] - [ - 2√(x) * √(x + 7)] + 4x
It looks exactly the same as before!! I'm just really confused by this problem, and I have a couple more like it, so I want to know if figuring this one out could help me solve the other ones.
I'm confused about FOILing the different sides, whether or not I can combine two square roots, and quite frankly, a lot of other things.
One of the options on the test is 9, and I think this is the answer, because I've inserted it into the original equation and it works, but I'm just confused about how to actually get 9 out of this..
Sorry for the long question. I hope it's not hard to understand. I'm just hoping someone can walk me through all the steps of solving a problem like this so I can do it easily in the future.
Found 2 solutions by greenestamps, MathTherapy:
Answer by greenestamps(13367)   (Show Source):
You can put this solution on YOUR website!

Your original equation is

You CAN start the problem by squaring both sides of the equation; but when you do that you end up with an equation involving an "uglier" square root. Reaching the final answer is almost always easier if you start by changing the equation so that there is only one radical on each side of the equation.

And in this particular example, with the "-2" on the right side, I would also, to avoid possible future confusion, move that term to the left hand side, making the equation

Now square both sides.

Now isolate the remaining radical and square both sides again.

or

We squared both sides of the equation in solving the problem, so some of the roots we ended up with might not satisfy the original equation, so we need t check. x = 1/9 does NOT satisfy the original equation; x = 9 does. So the unique solution to the given equation is x = 9.

ANSWER: x = 9

A final note....

I work with high school math students who often take timed competitive tests where the speed of getting the answer is important. While the intent here is almost certainly to solve the problem by formal mathematical methods, the problem can be solved informally VERY quickly using logical reasoning.

The original equation shows that a combination via addition or subtraction of the radicals sqrt(x+7) and sqrt(x) yields in an integer result. That means (x+7) and (x) must both be integer perfect squares. A little knowledge of perfect square integers immediately tells us that the only two perfect square integers that differ by 7 are 16 and 9.

So we quickly have our solution:
ANSWER: x = 9

Answer by MathTherapy(10858)   (Show Source):
You can put this solution on YOUR website!

Here is my problem. [SQRT(x + 7)] - 2[SQRT(x)] =-2 OR √(x + 7) - 2√(x) = -2 ------- Now, the steps I took to solve this problem are to first square both sides: [√(x + 7) - 2√(x)] * [√(x + 7) - 2√(x)] = 4 so then I FOIL the left side, resulting in: (x+7) - [√(x + 7) * - 2√(x)] - [ - 2√(x) * √(x + 7)] + 4x So then I thought to subtract (x+7) and (4x) to both sides - [√(x + 7) * - 2√(x)] - [ - 2√(x) * √(x + 7)] = 4 - 4x - x - 7 (I think I'm supposed to switch the sign, because I've subtracted it and moved it to the opposite side, right?) I think I'm correct up to this point, but now I have to square both sides again. I think this left hand side could be re-written as: -2[√(x + 7) * - 2√(x)] Is this right? I'm subtracting it from itself, a negative, which could simply multiplied by -2. Anyway, now I need to square this again, so I assume the -2 becomes a 4 and I FOIL them separately? FOILING the left side will get: [√(x + 7) * - 2√(x)] * [√(x + 7) * - 2√(x)] Which, when FOILed, looks like (x+7) - [√(x+7) * -2√(x)] - [ - 2√(x) * √(x + 7)] + 4x It looks exactly the same as before!! I'm just really confused by this problem, and I have a couple more like it, so I want to know if figuring this one out could help me solve the other ones. I'm confused about FOILing the different sides, whether or not I can combine two square roots, and quite frankly, a lot of other things. One of the options on the test is 9, and I think this is the answer, because I've inserted it into the original equation and it works, but I'm just confused about how to actually get 9 out of this.. Sorry for the long question. I hope it's not hard to understand. I'm just hoping someone can walk me through all the steps of solving a problem like this so I can do it easily in the future. ******************************* Here is my problem. [SQRT(x + 7)] - 2[SQRT(x)] =-2 OR √(x + 7) - 2√(x) = -2 ------- Now, the steps I took to solve this problem are to first square both sides: [√(x + 7) - 2√(x)] * [√(x + 7) - 2√(x)] = 4 so then I FOIL the left side, resulting in: (x+7) - [√(x + 7) * - 2√(x)] - [ - 2√(x) * √(x + 7)] + 4x <=== This is where you went WRONG! When FOILed, this's actually: , which results in: . See? So then I thought to subtract (x+7) and (4x) to both sides - [√(x + 7) * - 2√(x)] - [ - 2√(x) * √(x + 7)] = 4 - 4x - x - 7 (I think I'm supposed to switch the sign, because I've subtracted it and moved it to the opposite side, right?) <=== This is exactly how you need to proceed! ---- Squaring both sides OR 9x(x - 9) - 1(x - 9) = 0 (x - 9)(9x - 1) = 0 x - 9 = 0 OR 9x - 1 = 0 x = 0 + 9 OR 9x = 1 x = 9 OR x = (IGNORE) proves to be EXTRANEOUS, so sole solution is: x = 9 To some though, it's easier to solve, if one of the left-side RADICALS is MOVED to the right, 1st. But then, this's subjective. It looks exactly the same as before!! I'm just really confused by this problem, and I have a couple more like it, so I want to know if figuring this one out could help me solve the other ones. Hopefully, the above will clear up SOME/ALL confusion! I'm confused about FOILing the different sides, whether or not I can combine two square roots, and quite frankly, a lot of other things. Hopefully, the above will clear up SOME/ALL confusion! One of the options on the test is 9, and I think this is the answer, because I've inserted it into the original equation and it works, but I'm just confused about how to actually get 9 out of this. Yes, the solution is indeed 9, as seen above! Sorry for the long question. I hope it's not hard to understand. I'm just hoping someone can walk me through all the steps of solving a problem like this so I can do it easily in the future. Hopefully, this author has assisted you in understanding this problem, so you can understand and obtain SOLUTIONS to similar problems, more easily, more efficiently, and without confusion!

Question 48636: Please help. These problems look so easy but I just can't seem to get the right answer.
First Problem:
1/√3 + 4/√27 - 2/√12

Second Problem:
2 cubed root of 27x + 2 cubed root 64x
I came up with 2 answers:
14 cubed root of x -OR- 2 cubed root of 91x
Which one is correct??
Answer by ikleyn(53937)   (Show Source):
You can put this solution on YOUR website!
.
Please help. These problems look so easy but I just can't seem to get the right answer.
First Problem:
1/√3 + 4/√27 - 2/√12

Second Problem:
2 cubed root of 27x + 2 cubed root 64x
I came up with 2 answers:
14 cubed root of x -OR- 2 cubed root of 91x
Which one is correct??
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

        In the post by @consc198, first solution is irrelevant, while second solution is incorrect.

        For right solutions, see what follows.

F i r s t p r o b l e m It does not say what to do and what is required, but according to common sense, they want you to simplify and to reduce to simple canonic final form. + - = = + - = = = = = . ANSWER S e c o n d p r o b l e m + = Notice that 27 = 3^3, while 64 = 4^3. So, we continue the chain of equalities = = + = . the correct ANSWER

Solved.

As this person, @consc198, solves simple standard Math problems, he deserves to be excluded
from everywhere of an educational community, because he is not able to teach in a right way.

Question 1095268: how much xsquare -y square ? if x+y=66 xy=9

Found 4 solutions by KMST, ikleyn, greenestamps, MathTherapy:
Answer by KMST(5396)   (Show Source):
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ONE WAY:
Maybe we know about solving quadratic equations.
Sometimes we can solve a quadratic equation such as by factoring if we find two integers such that and .
Then those values for and are the solutions of the equation and the equation is really
.
The solutions to a quadratic equation of the form are always two numbers whose sum and product can be found are and respectively.
Unfortunately, sometimes those numbers are irrational, or even imaginary, and then factoring is not an option.
Then, w must use algebra to "complete the square" and then solve, or apply the dreaded quadratic formula
that says the solutions to an equation of the form are given by

To avoid confusion, I used for the variable instead of , and I prefer equations where the leading coefficient is , so I wrote my equation as .
I will make and to get .
The solutions will be the numbers and (or and ) that add up to and whose product is .
The quadratic formula tells me that the solution are given by

The solutions to the equation are and
One is and the other is , but there is no way to guess which was intended to be and which was intended to be .
and are
and

The possible answers are
and

ANOTHER APPROACH:
We know that . If we only knew the value of we could easily find the value of

We know that , but to calculate we would need the value of

We know that and we know the values of and
Substituting the known values we get --> -->
Now we can use that value of to calculate the values of and , and from that find the value of

Then

Multiplying times

Answer by ikleyn(53937)   (Show Source):
You can put this solution on YOUR website!
.
How much x square -y square ? if x+y=66 xy=9
~~~~~~~~~~~~~~~~~~~~~~~

Tutor @greenestamps provided the answer = .

This answer is correct, but incomplete.

This problem has a symmetry (x.y) <---> (y,x).

In other words, values x and y can be rearranged.

It means that together with the answer =
another answer = is valid and is possible, too.

So, the complete answer to the problem is THIS:

        - under given conditions, may have two different values.
           One possible value is ; another possible value is .

Answer by greenestamps(13367)   (Show Source):
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Given: x+y=66; xy=9

Find:

Answer by MathTherapy(10858)   (Show Source):
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Question 316943: simplify: sqrt (121) / (9)
a) sqrt (11) / sqrt (3)
b) 3 sqrt (11)
c) 11/3
d) sqrt (11) / (3)
Answer by MathTherapy(10858)   (Show Source):
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simplify: sqrt (121) / (9) a) sqrt (11) / sqrt (3) b) 3 sqrt (11) c) 11/3 d) sqrt (11) / (3) ****************** The other person's answer, "...d because the sqrt of 121 is 11 and the sqrt of 9 is 3," is PARTIALLY WRONG! If it's , then it's If it's , then it's

Question 1030250: I need help simplifying this expression:

I removed the common factor out of the square root to obtain , but the answer key says it is .
How is it possible? Am I missing out on a rule here?
Found 2 solutions by greenestamps, MathTherapy:
Answer by greenestamps(13367)   (Show Source):
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Consider this patern:

Given an expression to be simplified in the form , if you can modify the expression so the coefficient "b" on the inside radical is 2, then the expression can be simplified using that pattern.

In your example, you can take "4" out of the coefficient "8", leaving the required coefficient "2"; the "4" goes back inside the radical as :

The pattern now says you want to find integers a and b for which a+b=24 and ab=80. Those integers are 20 and 4, so

Answer by MathTherapy(10858)   (Show Source):
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I need help simplifying this expression: I removed the common factor out of the square root to obtain , but the answer key says it is . How is it possible? Am I missing out on a rule here? ************************************* This happens to be one of those RARE cases when you can actually factor out a COMMON factor, which happens to be a PERFECT SQUARE (in 4). This is what you did: = ----- Applying = ....At this point, you haven't fully simplified the expression, and should've continued as follows: ---- Changing 6 to 5 + 1, and 5 to 5*1 ---- Applying = --- Converting The above is in the form: , with , and so: then becomes: ----- Cancelling SQUARE and SQUARE ROOT = This certainly matches the answer key: ===== On the other hand, this author would've SIMPLIFIED the SURD from the onset, as follows: ----- Replacing 8 with factors, 2 & 4 ----- Converting 4 to ----- Applying = ---- Changing 24 to 20 + 4, and applying = ---- Converting The above is in the form: , with , and so: then becomes: ----- Cancelling SQUARE and SQUARE ROOT This certainly matches the answer key:

Question 973976: what is (4- square root of 8) divided by (2+ square root of 8) simplified

Answer by MathTherapy(10858)   (Show Source):
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what is (4- square root of 8) divided by (2+ square root of 8) simplified ********************************************* According to the other person, "I put this into the calculator at Mathway.com, and it comes out as: −4+3√2 (that's "three square root two")." Is this really "HELP?" Punching numbers on a calculator? Or, is this OUTRIGHT LAZINESS? * ---- Multiplying NUMERATOR and DENOMINATOR by , the DENOMINATOR'S conjugate ---- Converting to =

Question 78896: please help me simplify this problem?
sqrt/sqrt
Found 3 solutions by ikleyn, timofer, MathTherapy:
Answer by ikleyn(53937)   (Show Source):
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.
please help me simplify this problem?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The right way to simplify is THIS

         = = = .         ANSWER

                Solved completely and correctly.

According to commonly accepted agreements about square root,
the expression ' ' always goes from the square root as |a|, the absolute value of 'a'.

In this form, this transformation works universally for positive and negative values of ' a '.

The given problem is a standard TRAP to catch of those, who are unfamiliar with this trap for advance.

My post shows and teaches a standard way to avoid this trap.

As tutor @MathTherapy likes to say, " do not accept any other answer ".

Answer by timofer(159)   (Show Source):
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Answer by MathTherapy(10858)   (Show Source):
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please help me simplify this problem? sqrt/sqrt ************************************* The other person wrote, "Now, you need to see that , so you can also pull out a 4 from under the radical" How does this make sense? In what universe is ? As a result, his answer, is obviosly WRONG!! = = =

Question 669305: Please help me simplify this: sqrt(x^4y^7)
Answer by MathTherapy(10858)   (Show Source):
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Please help me simplify this: sqrt(x^4y^7) ************************************* The other person's answer, , is WRONG as he/she failed to SIMPLIFY this expression, completely. = =

Question 60849: solve for x by using the quadratic formula: 9x^2-6x+5=0
thanks so much
Answer by ikleyn(53937)   (Show Source):
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.
solve for x by using the quadratic formula: 9x^2-6x+5=0
thanks so much
~~~~~~~~~~~~~~~~~~~~~~~

        The solution by @jai_kos is incorrect.
        See my correct solution below.

9x^2-6x+5=0

It is the quadratic equation of the form.

ax^2+bx +c =0

Comparing the equations, we get
a = 9, b = -6 and c = 5

x =

x =

x =

x =

x = = .

Thus the given equation has no real solutions.
It has two conjugate solutions in complex numbers.

Solved correctly.

Question 60848: help on this please,,thanks
x+1= sqrt x+7
Answer by ikleyn(53937)   (Show Source):
You can put this solution on YOUR website!
.
help on this please,, thanks
x+1= sqrt(x+7)
~~~~~~~~~~~~~~~~~~~~~~~~

        The solution in the post by @jai_kos is incorrect.
        See my correct solution below.

x+1= sqrt(x+7)

Square on both sides, we get

(x+1)^2 = x +7
x^2 + 2x + 1 = x + 7

Reduce it to the standard form quadratic equation

x^2 + x - 6 = 0

Factor left side

(x+3)*(x-2) = 0

The roots of this equation are x = -3 and x = 2.
Direct check shows that x = 2 is the solution to the original equation, while x = -3 is an EXTRANEOUS solution.

ANSWER. The given equation has a unique solution in real numbers x = 2.

Solved correctly.

Question 681800: I'm trying to prove that

Answer by MathTherapy(10858)   (Show Source):
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I'm trying to prove that ******************* This author's proof is different from the one the other person who responded, provided. His method may not be what the person who needs help, is looking for. Then again, this hunch may be WRONG! Having said that, let's focus on the L.H.S. because that's what's needed to be proven to equal 2. + + ---- Changing 6 to 2(3) + ------- Changing 3 to + ----- Changing 4 to 3 + 1, 3 to , and 12 to 9 + 3 + ------ Converting The above is in the form: + , with , and so: + then becomes: + + ----- Cancelling SQUARE and SQUARE ROOT + QED!

Question 1107093: One pair of integers (x.y) solves , find x*y.
Answer by MathTherapy(10858)   (Show Source):
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One pair of integers (x.y) solves , find x*y. *************************************************************** ----- Replacing 4 with its PRIME factors, 2 & 2 ----- Converting 2 to ---- Changing 11 to 7 + 4 ---- Converting The above is in the form: , with , and so: then becomes: ----- Cancelling SQUARE and SQUARE ROOT √(4√(7+11)) = , is in the form: y + √x, with y = 2, and x = 7. Therefore, x*y = 7(2) = 14.

Question 1124474: How would you simplify the equation:
Sqrt(17-12sqrt2) in the form
(a+bsqrt2)
Thank you.
Answer by MathTherapy(10858)   (Show Source):
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How would you simplify the equation: Sqrt(17-12sqrt2) in the form (a+bsqrt2) Thank you. ********************************** Not an equation, but an expression, instead!! ----- Changing 12 to 2*6 ------ Converting 6 to ------ Applying ----- Changing 17 to 9 + 8, and 72 (in ) to 9*8 ------ Applying ------ Converting The above is in the form: , with , and so: then becomes: ----- Cancelling SQUARE and SQUARE ROOT

Question 263259: solve: x^5/6 + x^2/3-2x^1/2 =0
thanks!
Answer by ikleyn(53937)   (Show Source):
You can put this solution on YOUR website!
.
solve: x^5/6 + x^2/3 - 2x^1/2 = 0
~~~~~~~~~~~~~~~~~~~~~~~~~

        The solution in the post by @mananth is FATALLY incorrect.

        His first step is to raise all three addends in the left side of the equation to degree 6.
        But this step is not an equivalent transformation, so, starting from this point,
        his solution is inadequate.

        See my correct solution below.

The original equation is x^5/6 + x^2/3 - 2x^1/2 = 0. (1) It is the same as x^5/6 + x^4/6 - 2x^3/6 = 0. (2) Factor left side, taking x^3/6 out the parentheses as a common factor x^3/6*(x^2/6 + x^1/6 - 2) = 0. (3) One root is x = 0, generated by the common factor x^3/6. To find the roots generated by the expression in parentheses, introduce new variable t = x^1/6. Then the expression in parentheses is t^2 + r - 2. Its roots are = = = = . So, the roots are t = -2 and t = 1. Since t = x^1/6, we accept the positive root t = 1 and reject the negative root t = -2. Thus, finally we have the solutions to the original equation x = 0 and x = 1. ANSWER. The original equation has two real solutions x = 0 and x = 1.

Solved correctly.

Question 1094302: Solving by substitution with u

creates quadratic =

u = 2,-1
going back and using those two outputs in
and
and
Finally, I get and
But -2 can't be in a radical and would 4 turn into 2,-2 or just 2?
Answer by MathTherapy(10858)   (Show Source):
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Solving by substitution with u creates quadratic = u = 2,-1 going back and using those two outputs in and and Finally, I get and But -2 can't be in a radical and would 4 turn into 2,-2 or just 2? ****************************************************************** u = 2,-1 <=== This is okay! "going back and using those two outputs in and <=== Here's where I guess you got confused, and substituted 2 and - 1 for x in But, u = 2, as you mentioned above, NOT x = 2. And, because you'd substituted u for earlier, at this juncture, you need to BACK-SUBSTITUTE the value of u to get: ---- Squaring both sides (x - 4)(x + 1) = 0 x - 4 = 0 OR x + 1 = 0 x = 4 OR x = - 1 Now, you have 2 values for x that you can CHECK to ensure that they're VALID and NOT EXTRANEOUS. Also, u = - 1, as you mentioned above. And, because you'd substituted u for earlier, at this juncture, you need to BACK-SUBSTITUTE the value of u to get: Seeing that the square root of ANY expression is positive (> 0), it's obvious that u = - 1 is an EXTRANEOUS value. As such, x = 4, or x = - 1 (see above).

Question 569284: solve the following radical:
Answer by MathTherapy(10858)   (Show Source):
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solve the following radical: **********************************************< Just like "Rational-functions/875226", - 12 is NOT a solution. It's an EXTRANEOUS root. Only VALID and ACCEPTABLE answer:

Question 864099: Can you show me how to Rationalize the denominator and simply the equation
6 / the square root of 2 - the square root of 3.
Answer by MathTherapy(10858)   (Show Source):
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Can you show me how to Rationalize the denominator and simply the equation 6 / the square root of 2 - the square root of 3. ********************************************************************* = = =

Question 864097: Can you show me how to Rationalize the denominator and simply the equation the square root of 6 / the square root of 5 - the square root of 3.
Answer by MathTherapy(10858)   (Show Source):
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Can you show me how to Rationalize the denominator and simply the equation the square root of 6 / the square root of 5 - the square root of 3. ********************************************************************* = = =

Question 707329: How would you solve this equation?

Answer by MathTherapy(10858)   (Show Source):
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How would you solve this equation? ************************************** The other person's response, that "You get -10+6i or -10-6i (complex results)", is WRONG11 As the smaller radicand, 2x MUST be greater than or equal to 0, we get: . So, . This gives us: , with ---- Squaring both sides ----- Squaring both sides x - 8 = 0. <==== VALID, and ACCEPTABLE solution for x, in THIS case!!

Question 144143: Hello. Please help me solve this problem: I need to find the simplest radical form and the approximate answer of .

x = 0.8944
Answer by MathTherapy(10858)   (Show Source):
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Hello. Please help me solve this problem: I need to find the simplest radical form and the approximate answer of . x = 0.8944 ***************** ---- Multiplying by LCD, 2x ----- Squaring each side However, the negative x-value, is EXTRANEOUS, therefore leaving the sole VALID x-value, . Great job!! You got up to this point: , but needed to go a little further, by RATIONALIZING the DENOMINATOR, as demonstrated above. Your decimal approximation, x = 0.8944, is also CORRECT. I don't know why you sought help. You didn't need it! Again, great job!!

Question 798582: Simplify if necessary. Then rationalize the denominator.

Answer by MathTherapy(10858)   (Show Source):
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Simplify if necessary. Then rationalize the denominator. ************************** CORRECT answer: , or , and NOT as the other person states.

Question 459722: Simplify each expression by rationalizing the denominator.
3/sqrt(7)
2sqrt(2)/sqrt(5)
3sqrt(2)/sqrt(6)
2sqrt(5)/sqrt(12)
Answer by MathTherapy(10858)   (Show Source):
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Simplify each expression by rationalizing the denominator. 3/sqrt(7) 2sqrt(2)/sqrt(5) 3sqrt(2)/sqrt(6) 2sqrt(5)/sqrt(12) ****************** This problem "asks" to SIMPLIFY by "rationalizing the denominator," NOT providing a calculated value, as the other person did! , or , or , or

Question 904562:
Answer by MathTherapy(10858)   (Show Source):
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***************************** It is UNBELIEVABLE that the person who responded to this problem applied this RIDICULOUS approach. The person got up to , and UNBELIEVABLY, HE chose to, "complete the squares........" What would behoove someone to suggest such a thing to a person who asks for help with a math problem? Now, isn't SIMPLY x(x - 6) = 0, which results in values of 0 and 6 for x? Why would someone go through all that trouble to COMPLETE the SQUARE here? It's the same as using the quadratic equation formula to solve it, which is EXTREMELY RIDICULOUS and TOTALLY UNNECESSARY.....a TOTAL waste of time, in this author's opinion. Some people are probably more eccentric than is realized!!

Question 296793: Please help me solve this equation

Answer by MathTherapy(10858)   (Show Source):
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Please help me solve this equation ****************************** This is UTTERLY CRAZY!! Who ever heard of this: square everything <=== Who in their right mind would square both sides of a square root problem like this? Why do these people respond in this manner? This "HELP" is NO HELP at all!! Just leave the problem for someone who can handle it! BTW, the person claimed this to be an UNDEFINED equation. In other words, there are no solutions! Really!! Ha-ha-ha! --- Squaring BOTH sides, the CORRECT way ---- Dividing by GCF, 2 1 = 4(4 - x) --- Squaring each side 1 = 16 - 4x 1 - 16 = - 4x - 15 = - 4x This x-value, is VALID!!

Question 37745: Hi, I'm having trouble with this problem. Do you think you could help me?

Answer by MathTherapy(10858)   (Show Source):
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Hi, I'm having trouble with this problem. Do you think you could help me? *********************************************************************** Correct answer: , and NOT as the other person states!

Question 729072: square root of x+7=square root of 2x-3 (+2) not under the square root)
Answer by MathTherapy(10858)   (Show Source):
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square root of x+7=square root of 2x-3 (+2) not under the square root) ************************************************************************* I don't know what "X=507+338√2 ≈985.0042 from @lynnlo(4176) is all about. square root of x+7=square root of 2x-3 (+2) not under the square root) --- Squaring both sides ----- Squaring both sides (x - 42)(x - 2) = 0 x - 42 = 0 OR x - 2 = 0 x = 42 OR x = 2 However, x = 42 is an EXTRANEOUS solution, so ONLY solution is: x = 2

Question 519668: how do you solve the following:
+ =

Answer by MathTherapy(10858)   (Show Source):
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how do you solve the following: + = ****************************** One of the persons who responded states that , but this is WRONG!! x CANNOT equal . Of the 3 RADICAL expressions, 2x - 1 is the SMALLEST. So, , and ===> . So, we now get: + = , with + = = ----- Squaring both sides = 7x + 1 = 7x + 1 = 7x + 1 = 7x + 1 - 3x - 3 = 4x - 2 = ------ Squaring both sides 0 = (2x - 1)(x - 5) 0 = 2x - 1 OR 0 = x - 5 1 = 2x OR 5 = x As and , both solutions for x are VALID!

Question 701399: simplify
Answer by MathTherapy(10858)   (Show Source):
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simplify ==================================== The other person's answer, 15, is WRONG!! = = = = = = = = = =

Question 993742: Hello. I am having an issue solving this problem and I look to you for help. My problem is:
-+. By using prime factorization, I know that 12 = 2^2*3
50 = 5^2*2
72 = 3^2*2^3
Now, I plug these terms back in and I get:
-+ If I continue, I get:
-+
The answer key shows that the answer should be
- Can you see where I went wrong? I'm not coming up with the right answer.

Answer by MathTherapy(10858)   (Show Source):
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Hello. I am having an issue solving this problem and I look to you for help. My problem is: -+. By using prime factorization, I know that 12 = 2^2*3 50 = 5^2*2 72 = 3^2*2^3 Now, I plug these terms back in and I get: -+ If I continue, I get: -+ The answer key shows that the answer should be - Can you see where I went wrong? I'm not coming up with the right answer. ========================= - can NEVER be the simplified answer here. This answer must be for a different problem. Correct answer: ===================================================== Hello. I am having an issue solving this problem and I look to you for help. My problem is: -+. By using prime factorization, I know that 12 = 2^2*3 50 = 5^2*2 72 = 3^2*2^3 Now, I plug these terms back in and I get: -+ -+ If I continue, I get: -+ = +<==== Should be THIS, your FINAL answer!! You ALREADY have the correct answer, as you can see.

Question 1179144: For what values of c will x² +28x + c = 0 have no real solutions? Explain
Answer by ikleyn(53937)   (Show Source):
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.
For what values of c will x^2 +28x + c = 0 have no real solutions? Explain
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The given quadratic equation has no real solutions if and only if its discriminant is a negative value. The discriminant is d = 28^2 - 4c = 784 - 4c. The condition of negativity the discriminant is 784 - 4c < 0, or 4c > 784, c > 784/4 = 196. ANSWER. The given equation has no real solutions at c > 196.

Solved.

Question 787079: Simplify the expression. Assume that all variables are positive
√x/5*√x/20
Answer by MathTherapy(10858)   (Show Source):
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Simplify the expression. Assume that all variables are positive √x/5*√x/20 If , then the answer is NOT 10x, as stated by the other person who responded. = = = =

Question 99475: Perform the indicated division. Rationalize the denominator if necessary. Then simplify each radical expression
-9-sqrt(108) dived by 3
Answer by MathTherapy(10858)   (Show Source):
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Perform the indicated division. Rationalize the denominator if necessary. Then simplify each radical expression -9-sqrt(108) dived by 3 The answer is (see Question # 83444), and NOT as the other person states. , as he/she suggests! I wonder where these people learned their mathematics!

Question 293344: how would you solve this proof?

Answer by MathTherapy(10858)   (Show Source):
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how would you solve this proof? This is indeed a NESTED SURD. From the other person's response, let me pick up from this point: Start with the given equation. Let's focus on the L.H.S. of the equation. --- Converting 2 to ---- Changing 8 to 6 + 2, and 12 to 6 * 2 --- Converting 6 to and 2 to The above is now in the form: , with a being , and b being So, now becomes: ---- Cancelling square and sqrt = As seen, L.H.S. = R.H.S.

Question 485164: Write the following expression as a radical and simplify if possible.
(-64)^4/3
Answer by MathTherapy(10858)   (Show Source):
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Write the following expression as a radical and simplify if possible. (-64)^4/3 The other person's answer, 81, is WRONG!! = =

Question 732218: how do you do √50x√18?
Found 2 solutions by MathTherapy, ikleyn:
Answer by MathTherapy(10858)   (Show Source):
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how do you do √50x√18? √50 x √18 = 5√2 x 3√2 = 5(3)(√2 x √2) = 15√2 x √2 = 15√4 = 15(2) = 30

Answer by ikleyn(53937)   (Show Source):
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.
how do you do √50x√18?
~~~~~~~~~~~~~~~~~~~~~~

I treat the square roots as having positive values and 'x' as the multiplication sign. It is what should be told in the problem's description, but since it is omitted, I insert it to make your request sensible. Then * = = = 30. ANSWER

Solved.