tolong jawab dong nmr 14, beserta rumusnya

f(x) = ax^2 - bx -5

f(-1) => a + b - 5 =0

f(1) => a - b - 5 = -6
_______________ -

2b = 6

b = 3

a + b -5 =0

a + 3 -5 =0

a - 2 =0

a = 2

a + b = 2 + 3 = 5 D