Question

Factor -7x^3+21x^2+3x-9 by grouping. what is the resulting expression?

a) (3-7x)(x^2-3)
b) (7x-3)(3-x^2)
c) (3-7x^2)(x-3)
d) (7x^2-3)(3+x)​

Answer 1

c) (3-7x^2)(x-3)

Explanation:

-7x^3+21x^2+3x-9

Factor out a -7x^2 from the first two terms and a 3 from the last two terms

-7x^2 (x -3) +3(x-3)

Now factor out (x-3)

(x-3) (-7x^2+3)

Rearranging)

(x-3) (3-7x^2)