Factor completely: 15x^2 - 40x - 15.

-5 (3+8x+3x^2) this was my answer I'm sorry if I'd gotten it wrong

The answer to your question is 5 (x - 3) (x + 3)

Step-by-step explanation:

15x² - 40x - 15

Multiply the first and the last term (15) x (-15) = - 225

Find the prime factors of - 225

-225 3

- 75 3

- 25 5

- 5 5

-1

Find two numbers that added gives - 40 and multiply gives - 40 using the prime factors:

These numbers are - 45 (3 x 5 x 3) and 5

Write - 40 as the addition of the numbers just found - 40 = - 45 + 5

Write the original polynomial using these numbers 15x² - 45x + 5x - 15

Factor by grouping 15x (x - 3) + 5 (x - 3)

(x - 3) (15x + 5)

Factor by like terms the second term (x - 3) (5) (x + 3)