Which of the binomials below is a factor of this trinomial? 4x^2-7x-15 o a. 2x-5 o b. 4x+5 o c. 2x+5 o d. 4x-5

B

Step-by-step explanation:

Given

4x² - 7x - 15

To factorise 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 = 4 × - 15 = - 60 and sum = - 7

The factors are - 12 and + 5

Use these factors to split the x- term

4x² - 12x + 5x - 15 ( factor the first/second and third/fourth terms )

= 4x(x - 3) + 5(x - 3) ← factor out (x - 3) from each term

= (x - 3)(4x + 5) ← in factored form

Hence 4x + 5 is a factor of the trinomial → B