Question

Explain, in complete sentences, how you would factor 3x4 – 9x3 – 120x2.

Provide the factors.
this is what I have so far but im stuck...

Factor out 3x^2
(x^2-3x-40)
find two numbers that when multiplied together equal -40, and when added together equal -3
The factors are -8 and 5

Answer 1

3x^2(x^2-3x-40) -- 3x^2 is a factor of 3x4 – 9x3 – 120x2, when you divide the the given function by 3x^2, you would get x^2-3x-40, and when you multiply x^2-3x-40 by the 3x^2 you would get 3x4 – 9x3 – 120x2, so 3x^2 factors the function

now you have
3x^2(x^2-3x-40) -- -8 and 5 are the two numbers when multiplied, you get -40 and when added you get -3x
so it would be
3x^2(x^2-3x-40)
3x^2(x-8)(x+5)

Answer 2

hope that makes sense :)

Answer 3

Thanks a bunch! :D

Answer 4

No Problem