# How do you factor #2x^3 + 2x^2 - 84x#?

##### 2 Answers

Aug 13, 2016

#### Answer:

#### Explanation:

The first step is to take out the

#color(blue)"common factor"# of 2x

#rArr2x(x^2+x-42) ........ (A)# Now factorise the

#color(blue)"quadratic"# inside the bracket.Using the a-c method, find the factors of - 42 which sum to +1

These are +7 and - 6

#rArrx^2+x-42=(x+7)(x-6)# substituting these into (A) gives the factorised form.

#rArr2x^3+2x^2-84x=2x(x+7)(x-6)#

Aug 13, 2016

#### Answer:

#### Explanation:

And from this start:

And thus,