tolong di bantu ya kak

x^2 - 2x - 15 => (x - 5) (x + 3) = 0 => x1 = 5 dan x2 = -3

a. (x1 + 2)(x2 + 2) - 7 = (5 + 2)(-3 + 2) - 7 = -7-7 = -14
b. 1/x1 + 1/x2 = 1/5 - 1/3 = -2/15