If x -3 is a factor of x 2 - ax -15, then a =

Question

Philoid · Accepted Answer

Let, f(x) = x² - ax - 15

Since, (x -3) is a factor of f (x), so

f (3) = 0

3² - a (3) -15 = 0

9 - 3a - 15 = 0

a = -2