Factor completely 18x2 − 21x −15. 3(2x + 1)(3x − 5) 3(2x − 5)(3x + 1) 3(2x − 1)(3x + 5) 3(6x + 1)(x − 5)

3(2x + 1)(3x - 5)

Step-by-step explanation:

Given

18x² - 21x - 15 ← factor out 3 from each term

= 3(6x² - 7x - 5 ) ← factor the quadratic

Consider the factors of the product of the x² term and the constant term which sum to give the coefficient of the x- term.

product = 6 × - 5 = - 30 and sum = - 7

The factors are + 3 and - 10

Use these factors to split the x- term

6x² + 3x - 10x - 5 ( factor the first/second and third/fourth terms )

3x(2x + 1) - 5(2x + 1) ← factor out (2x + 1) from each term

(2x + 1)(3x - 5)

Then

18x² - 21x - 15 = 3(2x + 1)(3x - 5)

1 and 2

step-by-step explanation: