Question

Which is the completely factored form of 3xsquared
-12x-15?

Answer 1

3(x - 5)(x + 1).

Explanation:

3x^2 - 12x - 15

Dividing through by 3:

= 3(x^2 - 4x - 5)

We need 2 numbers whose sum is -4 and whose product = -5. That is -5 and +1 , so the factors are:

3(x - 5)(x + 1).