What number is represented by the letter in the identity below:

x2+2x-35 = (x+7) (x-a)

a = 5

Step-by-step explanation:

Given

x² + 2x - 35

Consider the factors of the constant term ( - 35) which sum to give the coefficient of the x - term ( + 2)

The factors are + 7 and - 5, since

7 * - 5 = - 35 and 7 - 5 = + 2, thus

x² + 2x - 35 = (x + 7) (x - 5)

Compare to (x + 7) (x - a)

with a = 5