F(x) : ax +b , (f o f)(x) : 16x - 15 , nilai a + b : ?

f(x) = ax + b

(f o f)(x) = f(f(x))
16x - 15 = a(ax + b) + b
16x - 15 = a²x + ab + b
16x - 15 = (a²)x - (-ab - b)

Maka
a² = 16
a = √16
a = 4

-ab - b = 15
-(4)b - b = 15
-5b = 15
b = 15/-5
b = -3

Maka
a + b = 4 + (-3) = 1

f(x) = ax + b

(fof)(x) = 16x - 15
a(ax + b) + b = 16x - 15
a²x + ab + b = 16x - 15

a² = 16
a = ± √16
a = 4 atau a = -4

ab + b = -15
• utk a = 4
4b + b = -15
5b = -15
b = -3

Maka :
a + b = 4 + (-3) = 1

• utk a = -4
-4b + b = -15
-3b = -15
b = 5

Maka :
a + b = -4 + 5 = 1

Kesimpulan :
a + b = 1

dengan a dan b yg berbeda