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Radicals/37498: This question is from textbook
hi i need your help on this problem please and thatnk you
6 the square root of 72
1 solutions

Answer 23123 by fractalier(2101) About Me  on 2006-05-12 11:28:07 (Show Source):
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Please see my earlier solution of this problem...the answer is
36rad(2)


Radicals/37503: This question is from textbook
hi umm i really need help on radicals i get it but i got suck so can you help? here it goes
6/72 i hope the slash helps i dont have the radical sigh
please and thank you
1 solutions

Answer 23121 by fractalier(2101) About Me  on 2006-05-12 11:24:15 (Show Source):
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See my earlier solution to this one...the answer is
36rad(2)


Inequalities/37516: This question is from textbook Intermediate Algebra
Find the area of a fenced yard with a length of 9 yards and width of 5 yards.
1 solutions

Answer 23120 by fractalier(2101) About Me  on 2006-05-12 11:23:26 (Show Source):
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If it is a rectangular yard, the area of it is found by
A = l x w (that is, length times width)
A = 9 x 5 = 45 square yards


Radicals/37504: This question is from textbook
hi umm i really need help on radicals i get it but i got suck so can you help? here it goes
6/72 i hope the slash helps i dont have the radical sign
please and thank you
1 solutions

Answer 23119 by fractalier(2101) About Me  on 2006-05-12 11:22:04 (Show Source):
You can put this solution on YOUR website!
If you mean to simplify 6rad(72), I can show you...
The idea is to separate (that is, factor) the radicand (the 72) into the largest perfect square within 72 and what's left.
Since 72 = 36 x 2, we have this:
6rad(72) =
6rad(36)rad(2)
But rad(36) = 6
So the final answer is found by
6rad(36)rad(2) =
(6)(6)rad(2) =
36rad(2)


Matrices-and-determiminant/37509: This question is from textbook College Algebra
Find det A, given A = [-1 0 1
2-1 3
0 1 5]
1 solutions

Answer 23118 by fractalier(2101) About Me  on 2006-05-12 11:17:57 (Show Source):
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This one is not easy to show here, but we can do it by the reduction-by-minors technique:
(-1) times the rows and columns not including the -1 MINUS
(0) times the rows and columns not including the 0 PLUS
(1) times the rows and columns not including the 1
so we get
(-1)(-5 - 3) - 0 + 1(2 - 0) =
8 - 0 + 2 =
10


Inequalities/37514: This question is from textbook
Evaluate 3x - 7y when x = -2 and y = -3.
1 solutions

Answer 23117 by fractalier(2101) About Me  on 2006-05-12 11:13:12 (Show Source):
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Here we substitute the given values for x and y into the expression
3x - 7y
to get
3(-2) - 7(-3) =
-6 - (-21) =
-6 + 21 =
15


Inequalities/37510: -2-4+7+3(-4)+17
1 solutions

Answer 23116 by fractalier(2101) About Me  on 2006-05-12 11:11:33 (Show Source):
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We need to apply the order of operations, PEMDAS, when doing problems such as this:
-2 - 4 + 7 + 3(-4) + 17 =
Thus multiplying comes before adding and subtracting, and we get
-2 - 4 + 7 - 12 + 17 =
Then we add and subtract left to right as we find them...yielding
6 as our answer


Inequalities/37512: This question is from textbook Intermediate Algebra
Simplify: -3[-4+1]/(-9)
1 solutions

Answer 23115 by fractalier(2101) About Me  on 2006-05-12 11:04:15 (Show Source):
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From -3[-4+1] / (-9), we need to combine what's in the parentheses first, giving us
(-3)(-3) / (-9) =
9 / -9 =
-1


Graphs/37417: The Graphs of ax+by=13 and ax-by=-3 instersect at (1,4). Find a and b.
1 solutions

Answer 23073 by fractalier(2101) About Me  on 2006-05-11 18:10:34 (Show Source):
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Since you know both lines go thru (1, 4), you can plug x = 1 and y = 4 in both and get
a + 4b = 13 and
a - 4b = -3
Now add equations and get
2a = 10 and
a = 5
You can also subtract equations and get
8b = 16
b = 2


Rational-functions/37416: Question goes like this....
Simplify each sum.
5x/x^2-9 + 2/x+4
1 solutions

Answer 23071 by fractalier(2101) About Me  on 2006-05-11 18:08:00 (Show Source):
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Not too much you can do here, but from
5x/x^2-9 + 2/x+4 we can combine fractions and get
[5x(x + 4) + 2(x^2 - 9)] / [(x + 4)(x - 3)(x + 3)] =
[5x^2 + 20x + 2x^2 - 18] / [(x + 4)(x - 3)(x + 3)] =
(7x^2 + 20x - 18) / [(x + 4)(x - 3)(x + 3)]


Probability-and-statistics/37414: 8.38 x 10^7 feet - 5.84 x 10^7 feet
1 solutions

Answer 23070 by fractalier(2101) About Me  on 2006-05-11 18:03:35 (Show Source):
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8.38 x 10^7 feet - 5.84 x 10^7 feet =
2.54 x 10^7 feet
Leave the powers of ten alone and merely subtract the decimals. Of course you have to be sure that your answer is in proper scientific notation, which it is...


Inverses/37415: my 3rd grader came home with this in her math homework & I can not figure it out _________ divided by 7 = 500
CAn you please help
1 solutions

Answer 23069 by fractalier(2101) About Me  on 2006-05-11 18:01:41 (Show Source):
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Yes. The question asks, "What number divided by 7 gives you 500?"
In algebra we show that as
x/7 = 500
We then multiply both sides by seven and get
x = 3500


Expressions-with-variables/37245: Solve each of the following systems by substitution.
4x – 12y = 5
-x + 3y = -1
1 solutions

Answer 23068 by fractalier(2101) About Me  on 2006-05-11 17:50:13 (Show Source):
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Please see my earlier solution of this problem.
It turns out that these two lines are parallel, thus no solution exists, and the system is said to be inconsistent.


Rational-functions/37413: what is an extraneous root?
1 solutions

Answer 23067 by fractalier(2101) About Me  on 2006-05-11 17:48:10 (Show Source):
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Sometimes you solve an equation and get two answers. By plugging them in to the original equation to check, you discover one (or both) do not work. That is an example of an extraneous root. Very common in rational expressions/equations, and equations containing radicals.


Graphs/37361: Is there a difference between solving a system of equations by the algebaraic method and the graphical method?
Thank you!:)
1 solutions

Answer 23066 by fractalier(2101) About Me  on 2006-05-11 17:46:00 (Show Source):
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Well, you should arrive at the same solution. The algebraic method is more precise because trying to estimate exact solutions from a written diagram can be difficult...for example, you may think the solution from your graph is (2, 3) but it may actually be (2 1/8, 2 15/16)...tis hard to tell sometimes...especially with handwritten graphs and thick pencil lines...


Expressions-with-variables/37411: a=b+3(4-c) if b equals 5 and c equals 2, what is the value of a?
1 solutions

Answer 23065 by fractalier(2101) About Me  on 2006-05-11 17:38:27 (Show Source):
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Okay if a = b + 3(4 - c) when b = 5 and c = 2, we can find a by plugging in values for b and c...so we have
a = b + 3(4 - c) = 5 + 3(4 - 2) = 5 + 3(2) = 5 + 6 = 11


Graphs/37362: What is the situation when two linear inequalities have no solution? And what conditions need to be satisfied for a system of linear inequalities to have its solution in the first quadrant?
Thank You :)
1 solutions

Answer 23064 by fractalier(2101) About Me  on 2006-05-11 17:35:48 (Show Source):
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Well for no solution to exist, the lines that govern them would need to be parallel and the shaded half-planes would have to be in opposite directions so that there is no overlapping of shaded areas. They could even represent the same line as long as they are both dotted and are shaded oppositely. For a system of inequalities to have a solution in the first quadrant, both (or all) shaded half-planes must intersect somewhere in the first quadrant.


Radicals/37409: hey. i'm pretty good at radicals, but i'm completely stumped on this one.
6√24x^5
______
18x
i'd appreciate your help.
1 solutions

Answer 23057 by fractalier(2101) About Me  on 2006-05-11 17:21:21 (Show Source):
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Okay...starting from
6(rad(24x^5)) / 18x
Let us pull the perfect squares out of the 24x^5 and we get
6(rad(24x^5)) / 18x =
6(rad(4x^4))(rad(6x)) / 18x =
6(2x^2)(rad(6x)) / 18x =
(12x^2)(rad(6x)) / 18x
Now do some cancelling...
2x(rad(6x)) / 3


Percentage-and-ratio-word-problems/37348: this year, 75% of the graduating class of Harriet Tubman High School had taken at least 8 math courses. Of the remaing class members, 60% had taken 6 or 7 math courses.What percent of the graduating class had taken fewer than 6 math courses?????
1 solutions

Answer 23056 by fractalier(2101) About Me  on 2006-05-11 17:15:29 (Show Source):
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If 75% of the students had taken 8 courses, 25% had not. Of these remaining 25%, 60% of them (or 60% of 25% = 15%) had taken 6 or 7 courses. Thus 90% (75% + 15%) of the students had taken 6, 7 or 8 courses.
Thus only 10% had taken less than 6 courses.
When working with percents, it is often easier to work with hundreds...in this case you could imagine there are 100 students and do the problem in real numbers instead of percentages.


Equations/37410: Solve: 1.3y + 4.4 = 0.8y + 4.1
1 solutions

Answer 23055 by fractalier(2101) About Me  on 2006-05-11 17:08:50 (Show Source):
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Please see my earlier solution...
y = -0.6


Equations/37408: Solve: 1.3y + 4.4 = 0.8y + 4.1
1 solutions

Answer 23054 by fractalier(2101) About Me  on 2006-05-11 17:07:48 (Show Source):
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From 1.3y + 4.4 = 0.8y + 4.1
we subtract 0.8y from both sides and get
0.5y + 4.4 = 4.1
Now subtract 4.4 from both sides and get
0.5y = -0.3
Now divide both sides by 0.5 and get
y = -0.6


logarithm/37294: Solve for x:
1) 3^x=729 I got 6
2) 6^x-28=-8 I got 10/3
3) 4ln 3x =15 I got 14.17
am I correct?
1 solutions

Answer 23053 by fractalier(2101) About Me  on 2006-05-11 16:59:05 (Show Source):
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Okay, let's see...
1) 3^x = 729 I got 6 ====> CORRECT
2) 6^x - 28 = -8 I got 10/3 ====> not correct. First add 28 to both sides...
6^x = 20
Now take the log of both sides and solve for x...
ln 6^x = ln 20
x = ln 20 / ln 6 and
x = 1.672
3) 4ln 3x =15 I got 14.17 ====> CORRECT. Here divide by four, then exponentiate and solve and we get
ln 3x = 15/4
3x = e^(15/4)
x = e^(15/4) / 3
x = 14.17


Signed-numbers/37296: 1/3 ÷ (-4/7)(-1/6) + (-1/18)
1 solutions

Answer 23052 by fractalier(2101) About Me  on 2006-05-11 16:50:56 (Show Source):
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Please see my earlier solution...47/126


Signed-numbers/37406: 1/3 ÷ (-4/7)(-1/6) + (-1/18)
1 solutions

Answer 23051 by fractalier(2101) About Me  on 2006-05-11 16:50:10 (Show Source):
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1/3 ÷ (-4/7)(-1/6) + (-1/18) =
1/3 + 4/42 + (-1/18) We need a lowest common denominator...here it's 126...so
1/3 + 4/42 + (-1/18) = 42/126 + 12/126 - 7/126 =
47/126


expressions/35707: This question is from textbook Introductory algebra
x^2+xy-y^2
__________
x+y
when x=6 and y=-2
1 solutions

Answer 23050 by fractalier(2101) About Me  on 2006-05-11 16:46:24 (Show Source):
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Let us evaluate
(x^2 + xy - y^2) / (x + y) when x = 6 and y = -2
The technique is to merely to plug in 6 for every x and -2 for every y...we get
(36 + (-12) - 4) / (6 - 2)=
20 / 4 =
5


Expressions-with-variables/37405: x-2y=2
2x+3y=11
use substitution method to solve system
if dependant or inconsistant please indicate
1 solutions

Answer 23049 by fractalier(2101) About Me  on 2006-05-11 16:42:34 (Show Source):
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From
x - 2 y = 2
2x + 3y = 11
Solve for x in the first and substitute into the second:
x = 2y + 2
2(2y + 2) + 3y = 11
4y + 4 + 3y = 11
7y + 4 = 11
7y = 7
y = 1
Then since x = 2y + 2, we have
x = 2(1) + 2
x = 4
Our solution is (4, 1)


Rational-functions/37253: My problem does not come from a textbook, but a worksheet.
I need to divide this rational expression:
((x^3-2x^2-63x)/(x^2-49)) / ((x^2-81)/x^2-7x))
sorry, I do not know how to make fractions or exponents on my computer.
1 solutions

Answer 23048 by fractalier(2101) About Me  on 2006-05-11 16:40:15 (Show Source):
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After you factor everything, then invert the denominator, and then cancel where you can the answer boils down to
x^2 / (x + 9)


logarithm/37293: After t years the value V of a car that cost $14,000is V(t)=14000(3/4)^t. Find the value of the car 2 years after it was purchased. I came up with $7,875.00...is this correct?
1 solutions

Answer 23046 by fractalier(2101) About Me  on 2006-05-11 16:36:38 (Show Source):
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Yes, it is correct.


Graphs/37399: There is no book for this problem. This is a problem asked by the professor. Please help.
1) An open-top box is to be constructed from a 4 by 6 foot rectangular cardboard by cutting out equal squares at each corner and the folding up the flaps. Let x denote the length of each side of the square to be cut out.
a) Find the function V that represents the volume of the box in terms of x.
Answer:



b) Graph this function and show the graph over the valid range of the variable x..
Show Graph here.




c) Using the graph, what is the value of x that will produce the maximum volume?
Answer.
1 solutions

Answer 23045 by fractalier(2101) About Me  on 2006-05-11 16:32:24 (Show Source):
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Well this is a bit difficult to show you without a diagram and graph, but here goes...
Since we are cutting a length x out of both ends of both the length and the width, the dimensions of the base of the box will be (6 - 2x) by (4 - 2x). It will have a height of x. Therefore the function for the volume is
V(x) = x(6 - 2x)(4 - 2x) = 4x^3 - 20x^2 + 24x
I can't show you the graph but you know x must be less than two.
To find the maximum volume, we take the derivative of V(x) and set it equal to zero...
dV/dx = 12x^2 - 40x + 24 = 0
Now solve for x
Use the quadratic formula to get
x = (5 ± rad(7)) / 3
But only one root works (as mentioned above), so the answer here is
x = (5 - rad(7)) / 3 or about .785 feet


Expressions-with-variables/37398: 2a=3b-13
b=2a+7
Use substitution method to solve system .
If system is dependant or inconsistant so indicate.
1 solutions

Answer 23044 by fractalier(2101) About Me  on 2006-05-11 16:22:44 (Show Source):
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From
2a = 3b - 13
b = 2a + 7
let us take the given value for b in the second equation and substitute it into the first equation, like this
2a = 3(2a + 7) - 13
2a = 6a + 21 - 13
2a = 6a + 8
-4a = 8
a = -2
Now using b = 2a + 7 we have
b = 2(-2) + 7
b = -4 + 7 = 3
So our solution is (-2, 3) and is a consistent system.


Miscellaneous_Word_Problems/37394: One hundred bushels of corn are to be divided among 100 men, women, and children. Men get 3 bushels each. Women get 2 bushels each. Children get 1/2 bushel each. How can the bushel be distributed? Is there more than on solution?

I do not have a textbook for this class.
1 solutions

Answer 23043 by fractalier(2101) About Me  on 2006-05-11 16:13:48 (Show Source):
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We can summarize what we have in two equations:
3M + 2W + (1/2)C = 100 (this is the bushels equation)
M + W + C = 100 (this is the number of people equation)
Since we have three unknowns but just two equations, there should be a number of solutions avalable.
One way to find some of them is to eliminate one variable by linear combination.
I multiplied the top equation by two and subtracted the bottom equation...
6M + 4W + C = 200
M + W + C = 100
yielding
5M + 3W = 100
so that any combination that satisfies this equation solves the problem...for example, eight men and twenty women (leaving 72 children) works...or 14 men, 10 women and 76 children...