Solve the equation?...and check my answers please.?

n^3 - 9n^2 - n + 9 = 0


(4x + 9y)^2 = (squaring binomials)


-25x^2 - 115x + 210 = -5(5x-7)(x+6)



check my answer to my other problems please!!!

-4m^2n^3 - 36m^2n^2 = 4m^2n^2 (n + 9)

9x (-x + 2) = -9x + 18x (is my answer right)

?2009-03-26T21:43:34Z

Favorite Answer

n^3 - 9n^2 - n + 9 = 0
When you factorize,the final answer is:
(n-1)(n+1)(n-9)=0


(4x + 9y)^2 =16x^2+72xy+81y^2

-4m^2n^3 - 36m^2n^2=-4m^2n^2(n+9)

9x (-x + 2)=-9x^2+18x


-25x^2 - 115x + 210 = -5(5x-7)(x+6) is correct

notthejake2009-03-26T21:27:21Z

n^3 - 9n^2 - n + 9 = 0
factor by grouping
(n^3 - 9n^2) - (n - 9) = 0
n^2 (n - 9) - 1(n - 9) = 0
(n^2 - 1)(n - 9) = 0
(n + 1)(n - 1)(n - 9) = 0

n + 1 = 0 ==> n = -1
n - 1 = 0 ==> n = 1
n - 9 = 0 ==> n = 9

so either n = 1 , -1, or 9

*****

(4x + 9y)^2 = (squaring binomials)
16x^2 + 36xy + 36xy + 81y^2 =
16x^2 + 72xy + 81y^2

*****

-25x^2 - 115x + 210 = -5(5x-7)(x+6)
-25x^2 - 115x + 210 = -5(5x^2 +23x - 42)
-25x^2 - 115x + 210 = -25x^2 - 115x + 210 yep, that's right

*****
GCF: -4m^2n^2, leaving n + 9

you left out a negative sign
-4m^2 n^3 - 36m^2 n^2 = -4m^2 n^2(n + 9)

***
left out an x^2:
9x(-x + 2) = -9x^2 + 18x

docktet2009-03-26T21:37:02Z

What are the instructions for the first problem? Is there some lead in material that might help us out. We could use a graphing calulator; but, I don't think that is what you are supposed to do.

If it is the solutions are n = -1, +1, 9.

Squaring the binomial has a rule of sq the first term of the binomial, sq the last term of the binomial, multiply the two pieces of the binomial then multiply by 2.

(4x)^2 +2(4x)(9y) +(9y)^2

16x^2 +72xy +81y^2


It looks like the third problem has already been factored. Good job.

The other two items are also correct. Congratulations.

GKumar2009-03-26T21:24:29Z

What is problem