Question

21x3 - 9x2 - 28x + 12

Answer 1

(7x-3) (3x^2 -4)

Explanation:

21x^3 - 9x^2 - 28x + 12

We can factor by grouping

Factor out 3x^2 from the first two terms and -4 from the last two

21x^3 - 9x^2 - 28x + 12

3x^2 ( 7x-3) -4(7x-3)

Now factor out (7x-3)

(7x-3) (3x^2 -4)