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Recent problems solved by 'vleith'

vleith answered: 2822 problems
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Rational-functions/333684: I am attempting to solve this
(2x-6)/(x-4)*7x/(3x-9)
please help
1 solutions

Answer 239112 by vleith(2825) About Me  on 2010-08-21 21:21:13 (Show Source):


Equations/333705: Simplify the following expression:
-3(-2x-v)-3(-v+x)
1 solutions

Answer 239110 by vleith(2825) About Me  on 2010-08-21 21:16:51 (Show Source):
You can put this solution on YOUR website!
-3%28-2x-v%29-3%28-v%2Bx%29
6x%2B3v+%2B3v-3x
3x+%2B+6v
Here is a plot
http://www.wolframalpha.com/input/?i=-3%28-2x-v%29-3%28-v%2Bx%29


Quadratic_Equations/333133: Solve the following quadratic equations: P^2+6p=0
1 solutions

Answer 238689 by vleith(2825) About Me  on 2010-08-19 15:26:11 (Show Source):
You can put this solution on YOUR website!
p%5E2+%2B+6p=0
p%28p%2B6%29+=+0
so p=0 or p+6=0
thus p=0 or p =-6
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 1x%5E2%2B6x%2B0+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%286%29%5E2-4%2A1%2A0=36.

Discriminant d=36 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-6%2B-sqrt%28+36+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%286%29%2Bsqrt%28+36+%29%29%2F2%5C1+=+0
x%5B2%5D+=+%28-%286%29-sqrt%28+36+%29%29%2F2%5C1+=+-6

Quadratic expression 1x%5E2%2B6x%2B0 can be factored:
1x%5E2%2B6x%2B0+=+1%28x-0%29%2A%28x--6%29
Again, the answer is: 0, -6. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B6%2Ax%2B0+%29


Square-cubic-other-roots/333131: The formula v=square root of 20L can be used to estimate the speed of a car, v, in miles per hour, based on the length, L, in feet, of its skid marks upon sudden braking on a dry asphalt road. If a car is involved in an accident and its skid marks measure 405 feet, at what estimated speed was the car traveling when it applied its brakes just prior to the accident?
Show your work.
1 solutions

Answer 238688 by vleith(2825) About Me  on 2010-08-19 15:24:03 (Show Source):
You can put this solution on YOUR website!
v+=+sqrt%2820l%29
given l = 405, find v
v+=+sqrt%2820%2A405%29
v+=+sqrt%288100%29
v+=+90
90 mph, tisk tisk tisk :(


Square-cubic-other-roots/333023: Please show me how to find the area of a square with the dimension of 1+square root of 2? Thanks
1 solutions

Answer 238619 by vleith(2825) About Me  on 2010-08-19 07:29:39 (Show Source):
You can put this solution on YOUR website!
The length of one side is L+=+1+%2B+sqrt%282%29
The area of a square is given by the L%5E2
Area+=+%281%2Bsqrt%282%29%29%5E2
Area+=+%281%2Bsqrt%282%29%29%281%2Bsqrt%282%29%29
Area+=+1%2A1+%2B+1%2Asqrt%282%29+%2B+sqrt%282%29%2A1+%2B+%28sqrt%282%29%29%5E2+
Area+=+1+%2B+2%2Asqrt%282%29+%2B+2
Area+=+3+%2B+2%2Asqrt%282%29
http://www.wolframalpha.com/input/?i=%281%2Bsqrt%282%29%29^2


expressions/333014: Find three ordered pairs that satisfy the equation.
y = -3x + 5
1 solutions

Answer 238618 by vleith(2825) About Me  on 2010-08-19 06:46:50 (Show Source):
You can put this solution on YOUR website!
Just plug and play.
Pick a value for x, then use that value of x to find y
for instance, pick x = 0
y+=+-%283%2A0%29+%2B+5
y+=+-0+%2B+5
y+=+5
So one ordered pair is (0,5)
Pick another value for x. Let's pick x = 1
y+=+-%283%2A1%29+%2B+5
y+=+-3+%2B+5
y+=+2
A second ordered pair is (1,2)
Use the same process to find as many ordered pairs as you want


Equations/333016: what is the value of x and y in the equation: 1/2x+1/3y=2
Ihave tried up to x=4-2y/3
y=-3/2(x-4)
1 solutions

Answer 238617 by vleith(2825) About Me  on 2010-08-19 06:43:38 (Show Source):
You can put this solution on YOUR website!
Your value for x is correct
Let's do y
x%2F2+%2B+y%2F3+=+2
y%2F3+=+2+-+x%2F2
y+=+6+-+%283x%29%2F2


Polynomials-and-rational-expressions/332818: graph the following function
f(x) = abs value of x divided by x
1 solutions

Answer 238466 by vleith(2825) About Me  on 2010-08-18 14:26:34 (Show Source):
You can put this solution on YOUR website!
use wolframaplha to plot this type of thing
http://www.wolframalpha.com/input/?i=|x|%2Fx


Equations/332823: 4x-2=1
thank you
1 solutions

Answer 238465 by vleith(2825) About Me  on 2010-08-18 14:25:17 (Show Source):
You can put this solution on YOUR website!
4x-2=1 add 2 to both sides
4x+=+3 divide both sides by 4
x+=+3%2F4


Distributive-associative-commutative-properties/332830: I think that this prb is distributive
(z+5)x = z*x+5*x
would it be
zx +5x for the answer or is it z5x(with x to the 2nd power)?
1 solutions

Answer 238464 by vleith(2825) About Me  on 2010-08-18 14:24:13 (Show Source):
You can put this solution on YOUR website!
zx +5x
you got it the first time :)


Expressions-with-variables/332829: Write an equation based on the sentence, then solve for x. Show all work.
A number x is five more than two times x minus three
1 solutions

Answer 238463 by vleith(2825) About Me  on 2010-08-18 14:23:22 (Show Source):


expressions/332746: please help me solve 4x+3=7 please show the steps
1 solutions

Answer 238427 by vleith(2825) About Me  on 2010-08-18 07:50:59 (Show Source):
You can put this solution on YOUR website!
4x%2B3+=+7 subtract 3 from each side
4x+%2B+3+-+3+=+7-3
4x+=+4 divide both sides by 4
{{4x/4 = 4/4}}}
x+=+1
Veerify your answer
Does %284%2A1%29+%2B+3++=+7???


percentage/332748: Find 32 out of 38 in percentage. Thank you
1 solutions

Answer 238426 by vleith(2825) About Me  on 2010-08-18 07:49:27 (Show Source):
You can put this solution on YOUR website!
Part%2FWhole%2A100 is percent
32%2F38%2A100
84.21%


Evaluation_Word_Problems/332749: MAN JUMPS 3 FENCES TO AN APPLE TREE HE PICKS APPLES ON THE WAY BACK HE MUST GIVE EACH FARMER AT THE FENCE 1/2 OF WHAT HE HAS + 1/2 AN APPLE AFTER ALL 3 FENCES HE'S LEFT WITH ONE HOW MANY DID HE START WITH
1 solutions

Answer 238425 by vleith(2825) About Me  on 2010-08-18 07:48:16 (Show Source):
You can put this solution on YOUR website!
Do this one backwards
After the last fence, he has 1 apple.
Before the fence he had x apples
You are told x%2F2+-+1%2F2+=+1
x%2F2+=+3%2F2
x+=+3 so he hads 3 apples before the last fence.
Now go back to fence 2
3+=+y%2F2+-+1%2F2
7%2F2+=+y%2F2
y+=+7 He had 7 apples before he hopped the second fence
Now all the way back to the fence closest to the tree
7+=+z%2F2+-+1%2F2
15%2F2+=+z%2F2
z+=+15
He started with 15 apples
He had to give 8 apples to the first farmer
4 apples to the second farmer
2 apples to the last farmer
and he ges one lousy apple for all his hard work and fence jumping
I hope it was worth it.
How about THEM apples :)


Probability-and-statistics/332750: a student has to answer 10 questions, choosing at least 4 from each of part A and part B. If there are 6 questions in part A and 7 in part B, in how many ways can the student choose 10 questions ?
1 solutions

Answer 238424 by vleith(2825) About Me  on 2010-08-18 07:42:02 (Show Source):
You can put this solution on YOUR website!
Let's pick from type A first.
We need to pick 4.
First pick has 6 choices
Second one now has 5
Third 4
Fourth 3
That leaves 2 extra type As
Now let's pick 4 from type B
Fifth pick has 7 choices
Sixth has 6
Seventh 5
Eight 4
That leaves 3 more type B.
We have two more picks to make and 5 question left to pick from
Ninth has 5 choices
Tenth has 4
Now, do the math
6%2A5%2A4%2A3+%2A+7%2A6%2A5%2A4+%2A+5%2A4
Solve that and there you go!



Equations/332540: -3x^7+ 42x^3
Please help.
1 solutions

Answer 238290 by vleith(2825) About Me  on 2010-08-17 12:00:49 (Show Source):
You can put this solution on YOUR website!
-3x%5E7%2B+42x%5E3
-3x%5E3%28x%5E4-14%29
See this URL for a plot
http://www.wolframalpha.com/input/?i=-3x^7%2B42x^3


Quadratic_Equations/332538: simplify and do not use negative exponents in the answer
(4x^5y^-6)^3
1 solutions

Answer 238289 by vleith(2825) About Me  on 2010-08-17 11:58:26 (Show Source):


Equations/332530: x^2-16<= 0
1 solutions

Answer 238288 by vleith(2825) About Me  on 2010-08-17 11:55:59 (Show Source):
You can put this solution on YOUR website!
Find the roots.
x%5E2-16%3C=+0
%28x-4%29%28x%2B4%29%3C=0
root at x = 4 and x = -4
Now pick a value less than -4. let's say -10.
When x=-10, then 100-16+=+84 which is > 0
Pick a value between the two root. Say x=0
When x=0 0-16=+-16 which is < 0
Pick a value greater than 4, say 10
Again 100-16=+84 which is greater than 0.
So points to the left of -4 and to the right of 4 do not satisfy the inequality.
The plot will be all points above the curve x^2-16 and below the x axis, between -4 and 4
See this URL for a plot
http://www.wolframalpha.com/input/?i=x^2-16%3C%3D0


Equations/332534: (2x^2y)^3 * (x^5y^3)^2
Please help.
1 solutions

Answer 238286 by vleith(2825) About Me  on 2010-08-17 11:49:45 (Show Source):
You can put this solution on YOUR website!
%282x%5E2y%29%5E3+%2A+%28x%5E5y%5E3%29%5E2 expand using power to power
%282%5E3%2A%28x%5E2%29%5E3%2Ay%5E3%29+%2A+%28%28x%5E5%29%5E2%2A%28y%5E3%29%5E2%29
8%2Ax%5E6%2Ay%5E3+%2A+x%5E10%2Ay%5E6
8%2Ax%5E6%2Ax%5E10%2Ay%5E3%2Ay%5E6 reorder using commumutation
8%2Ax%5E16%2Ay%5E9 collect like terms and use power times power rule


test/331487: I have asked for help on this story problem before however I have never heard back so I am still need of some help with solving this story problem.
In 1991 the life expectancy of males in a certain country was 63.2 years. In 1996 it was 65.7 years. Let E represent the life expectancy in year t, and let + represent the number of years since 1991.
The linear function E(t) that fits the data is E)t)=_____t + _____.
Use the function to predict the life expectancy of males in 2006.
E (15)= _____ and round to the nearest tenth.
Thanks for your help :o)
1 solutions

Answer 237605 by vleith(2825) About Me  on 2010-08-13 06:37:37 (Show Source):
You can put this solution on YOUR website!
Use the info provided to create a linear model of Life Expenctency.
You are given two points. With that data you have enough information to create the equation for a line.
First let's find the slope of the line
Slope = %28y%5B2%5D+-+y%5B1%5D%29+%2F+%28x%5B2%5D+-+x%5B1%5D%29
You are given the two data points (1991,63.2) and (1996, 65.7)
So the slope is %2865.7-63.2%29%2F%281996+-+1991%29 = 2.5%2F5+=+1%2F2
The problem says to model the Life Expectancy where t is the 'number of years since 1991"
So
E%28t%29+=+%281%2F2%29+t+%2B+63.2 that uses the slope we found above as the rate of change year to year. It also uses the expectency in the year 1991 as the starting point.
Check this now. In year 1991, t = 1991-1991 = 0. So E%280%29+=+0%2At+%2B+63.2+=+63.2 which is correct
IN 1996, t = 1996-1991 = 5. So E%285%29+=+%281%2F2%29%2A5+%2B+63.2+=+2.5%2B63.2+=+65.7 which is correct
You are then asked to use the equation to extrapolate the data to the year 2006
So, 2006-1991 = 15
E%2815%29+=+15%2F2+%2B+63.2+=+7.5+%2B+63.2+=+70.7
Again, this is just a model. There is nothing to suggest that Life expectency is linear. But that is all the data you have, so you have to go with that.
Make sense?


Linear_Algebra/331332: Simplify (-4b+9h)+(-14h)
1 solutions

Answer 237460 by vleith(2825) About Me  on 2010-08-12 16:02:17 (Show Source):


expressions/331327: solve the formula for the indicated letter
x = w+y+z
-------- for y
5

I am confused on how to do this problem. Please help
1 solutions

Answer 237459 by vleith(2825) About Me  on 2010-08-12 16:01:37 (Show Source):


Radicals/331330: Simplify by factoring, assume that all expressions under the radical represent non-negative numbers.
Please show each step? Thank you.
∜(162x^4 y^6 )
Thank you again
1 solutions

Answer 237458 by vleith(2825) About Me  on 2010-08-12 16:00:13 (Show Source):


Equations/331329: solve the equation

a/5 - 1/5 = -2


please help me I am confused
1 solutions

Answer 237457 by vleith(2825) About Me  on 2010-08-12 15:56:01 (Show Source):
You can put this solution on YOUR website!
a%2F5+-+1%2F5+=+-2 multiply thru by 5
5a%2F5+-+5%2F5+=+-2%2A5
a+-+1+=+-10
a+=+-9


Rational-functions/331326: Hello,
Solve.
5sqrt24y - 1 =0
The solution is y=?
I hope I put this right so someone can understand.
Thank You!
1 solutions

Answer 237455 by vleith(2825) About Me  on 2010-08-12 15:54:40 (Show Source):
You can put this solution on YOUR website!
Not sure if this is what you wrote. If not, try again and use lots of parens to make sure
5%2A+sqrt%2824y%29+-+1+=+0
Hope it is. Because that is what we will solve here :)
5%2A+sqrt%2824y%29+-+1+=+0
5%2A+sqrt%2824y%29+=+1
sqrt%2824y%29+=+1%2F5
24y+=+%281%2F5%29%5E2
24y+=1%2F25
y+=+1+%2F%2825%2A24%29
y+=+0.00166667


Equations/331324: solve using addition and multiplication principles

4n - 24(less than or = to)3 (4n + 8)

I did not know how to type this < with a line under it so I just wrote it out.
1 solutions

Answer 237451 by vleith(2825) About Me  on 2010-08-12 15:49:06 (Show Source):
You can put this solution on YOUR website!
4n+-+24+%3C=+3+%284n+%2B+8%29 expand
4n+-24+%3C=+12n+%2B+24 collect like terms
4n+-+12n+%3C=+24+%2B+24
-8n+%3C=+48 isolate variable
+n+%3E=+-48%2F8 remember to flip the sign when dividing or multiplyig an inequality by a negative number
+n+%3E=+-6
see here for a plot
http://www.wolframalpha.com/input/?i=4n+-+24+%3C%3D+3+%284n+%2B+8%29


Polynomials-and-rational-expressions/331319: solve using the addition and multiplication principles
0.6x+14+x>2x+15-0.5x

could someone please help me with this problem?
1 solutions

Answer 237442 by vleith(2825) About Me  on 2010-08-12 15:45:45 (Show Source):
You can put this solution on YOUR website!
0.6x%2B14%2Bx%3E2x%2B15-0.5x collect like terms on each side
0.6x+%2Bx+%2B+14+%3E+2x-0.5x+%2B+15
1.6x+%2B+14+%3E+1.5x+%2B+15 collect like terms and simplify
0.1x+-+1.5x+%3E+15+-+14
0.1x+%3E+1 isolate variable
x+%3E+1%2F0.1
x+%3E+10
Look here for a plot
http://www.wolframalpha.com/input/?i=0.6x%2B14%2Bx%3E2x%2B15-0.5x


Probability-and-statistics/331320: can you really help with math?
1 solutions

Answer 237439 by vleith(2825) About Me  on 2010-08-12 15:40:30 (Show Source):
You can put this solution on YOUR website!
If you have a question, post it.


Polynomials-and-rational-expressions/331192: solve. w^2-5w-50=0
1 solutions

Answer 237407 by vleith(2825) About Me  on 2010-08-12 08:06:41 (Show Source):
You can put this solution on YOUR website!
You can factor this or use the quadratic equation
w%5E2-5w+-+50+=+0
%28w-10%29%28w%2B5%29+=+0
w = 10 or w=-5
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 1x%5E2%2B-5x%2B-50+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%28-5%29%5E2-4%2A1%2A-50=225.

Discriminant d=225 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--5%2B-sqrt%28+225+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-5%29%2Bsqrt%28+225+%29%29%2F2%5C1+=+10
x%5B2%5D+=+%28-%28-5%29-sqrt%28+225+%29%29%2F2%5C1+=+-5

Quadratic expression 1x%5E2%2B-5x%2B-50 can be factored:
1x%5E2%2B-5x%2B-50+=+1%28x-10%29%2A%28x--5%29
Again, the answer is: 10, -5. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B-5%2Ax%2B-50+%29


Polynomials-and-rational-expressions/331188: Add. Simplify if possible. 5r/r^2-9+r/r-3
1 solutions

Answer 237406 by vleith(2825) About Me  on 2010-08-12 08:04:24 (Show Source):


Polynomials-and-rational-expressions/331189: Solve for x. 4x(x-5)-5x(x-4)=-1
1 solutions

Answer 237405 by vleith(2825) About Me  on 2010-08-12 08:00:26 (Show Source):
You can put this solution on YOUR website!
4x%28x-5%29-5x%28x-4%29=-1
4x%5E2+-+20x+-5x%5E2+%2B+20x+=+-1
-x%5E2+=+-1
x%5E2+=+1
x=1 and x= -1
Check your answers by pluggin in those 2 values for x, one at a time, and verifying the equality is 'true'