# Answers Check & Question

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• Apr 29th 2012, 07:37 AM
Kibbygirl
Answers Check & Question
Are these correct?

1. Multiply:
(10z+5)(z2 - 2z+10)

10z3 - 15z2 + 90z + 50

2. Divide:
16r3 - 12r2+ 60r + 16
------------------------
8r+2
2(r2 - r +4)

3. Divide Synthetically:
(2m3 + 5m2 + 6m -4) / (m +1)

2m2 + 3m + 3 R= -7/m+1

4. Subtract 13r2 - 9r + 3 from 7r2- 4r - 8

-6r2+ 13r +5

5. Divide:
18r3 - 9r2+34r +45
--------------------
6r + 5

3r2 - 4r + 9

6. Factor:
uv2 - 4 - v2+ 4

(u+1)(v2 + 4)

7. Factor:
x2(y-7)2 + 5x(y-7)2 +4(y-7)2

(y-7)2(x+4)(x-1)

8.Factor:
x3 + 125

(x+5)(x2-5x+25)

9. Factor:
16a4 - 1
(4a2+1)(4a2- 1)

10. If g(t) = 2t2+11t-10, find t such that g(t) = 11

g(t) = 353

11. Evaluate:
4x2y2+2x2y - 3xy2- 3xy + 6 when x= -2 and y = 2

-2

12. If P(y) = 1/2y -1 then find y such that P(y)= -5

P(y) = - 13/2

And I need help setting up this problem:
Solve this equation:
n3+80n=18n2

Would you set it up as n3+80n+18n2= 0 ?
I'm not sure what my steps need to be to set it up to try and solve it.

Thank you for any help!
• Apr 29th 2012, 08:44 AM
skeeter
Re: Answers Check & Question
allow me to introduce you to Wolfram Alpha ...

expand (10z+5)*(z^2 - 2z+10) - Wolfram|Alpha
• Apr 29th 2012, 01:49 PM
Kibbygirl
Re: Answers Check & Question
I've looked at Wolfram Alpha and many of what I input is not being understood. I am not sure what I am doing wrong with imputing the information? I really need to know if my answers are correct because these are being used as notes for my final tomorrow.
• Apr 29th 2012, 02:55 PM
Plato
Re: Answers Check & Question
Quote:

Originally Posted by Kibbygirl
I've looked at Wolfram Alpha and many of what I input is not being understood. I am not sure what I am doing wrong with imputing the information? I really need to know if my answers are correct because these are being used as notes for my final tomorrow.

Can you show what you tried at Wolfram Alpha that would not work.
You might Look at this page..
Using those examples may give you some ideas.
• Apr 29th 2012, 03:01 PM
skeeter
Re: Answers Check & Question
the following are incorrect ...

4, 6, 7, 10, 11, and 12

9 is incomplete

$\displaystyle n^3+80n=18n^2$

$\displaystyle n^3-18n^2+80n = 0$

start by factoring out an $\displaystyle n$ , then factor the resulting quadratic factor
• Apr 29th 2012, 03:21 PM
Kibbygirl
Re: Answers Check & Question
#10 and #12 are ones that it doesn't seem to understand and I am unsure how to put them in so it can understand them. I didn't see it on the examples page.
• Apr 29th 2012, 03:23 PM
Kibbygirl
Re: Answers Check & Question
Ok thank you. So 1-3, 5, 8 are all incorrect?
• Apr 29th 2012, 03:27 PM
skeeter
Re: Answers Check & Question
Quote:

10. If g(t) = 2t^2+11t-10, find t such that g(t) = 11
$\displaystyle 2t^2+11t-10 = 11$

$\displaystyle 2t^2+11t-21 = 0$

factor and solve

Quote:

12. If P(y) = 1/2y -1 then find y such that P(y)= -5
$\displaystyle \frac{1}{2y} - 1 = -5$

$\displaystyle \frac{1}{2y} = -4$

$\displaystyle -\frac{1}{4} = 2y$

$\displaystyle -\frac{1}{8} = y$
• Apr 29th 2012, 03:30 PM
Kibbygirl
Re: Answers Check & Question
Nevermind, I misread your above post.
• Apr 29th 2012, 03:34 PM
Plato
Re: Answers Check & Question
Quote:

Originally Posted by Kibbygirl
#10 and #12 are ones that it doesn't seem to understand and I am unsure how to put them in so it can understand them. I didn't see it on the examples page.

Well look at this,
• Apr 29th 2012, 05:35 PM
Kibbygirl
Re: Answers Check & Question
How would I put #7 above into the Wolfram site? This problem:
Factor:
x2(y-7)2 + 5x(y-7)2 +4(y-7)2
• Apr 29th 2012, 05:39 PM
skeeter
Re: Answers Check & Question
Quote:

Originally Posted by Kibbygirl
How would I put #7 above into the Wolfram site? This problem:
Factor:
x2(y-7)2 + 5x(y-7)2 +4(y-7)2

link ...

factor x^2(y-7)^2 + 5x(y-7)^2 +4(y-7)^2 - Wolfram|Alpha
• Apr 29th 2012, 06:04 PM
Kibbygirl
Re: Answers Check & Question
Thanks skeeter. I typed it in but I must have had spaces in the wrong spot. For #6 above - which I see I had a typo and left off the u on the end after the second 4... --- ; uv2 - 4 - v2+ 4u is the correct answer (u-1)(v2+4)?