Question

Which of the following is a factor of 3x^3-12x?

3x-4

x+2

x+3

x-4

Answer 1

x + 2

Explanation:

given

3x³ - 12x ← factor out 3x from each term

= 3x(x² - 4) ← x² - 4 is a difference of squares, hence

= 3x(x - 2)(x + 2) ← fully factorised

hence x + 2 is a factor of the polynomial

Answer 2

x + 2

Explanation:

3x^3 - 12x

=3x(x^2 - 4)

= 3x(x + 2)(x - 2)

so (x+2), (x - 2) and 3x are the factors of 3x^3 - 12x

answer:

x + 2