a.1 b.3 c.5 d.8 e.10 jwbnya pke cara ya

f(x) = x + 2 dan g(x) = 15/x
(g o f)(x) = g(f(x))
= 15/f(x)
= 15/(x + 2)
Misal 15/(x + 2) = y
=> xy + 2y = 15
=> xy = 15 - 2y
=> x = (15 - 2y)/y
(g o f)^-1 (x) = (15 - 2x)/x

(f^-1 o g^-1)(x) = 1
(g o f)^-1(x) = 1
(15 - 2x)/x = 1
15 - 2x = x
15 = 3x
x = 5

g(x) = y =15/x
y =15/x
x = 15/y => g'(x) = 15/x

f(x) = y = x + 2
y = x + 2
x = y - 2 => f'(x) = x - 2

(f'•g')(x) = f'(g'(x))
= 15/x - 2
= 15/x - 2x/x

(f'•g')(x) = 1
15/x - 2x/x = 1
15 - 2x = x
15 = x + 2x
15 = 3x
15/3 = x
5 = x

(C)