jika f(x)=2x+3 dan g(x) =9 - x,nilai dari (f o g)-1(-9)=

f(x)= 2x  + 3
g(x) = 9 - x

(fog)(x) = f{ g(x)}
= f (9 - x)
= 2(9 - x) + 3
= 18 - 2x + 3
= 21 - 2x

fog(x) = 21 - 2x
(fog)⁻¹(21- 2x) =  x
(fog)⁻¹ (-9 )=
21 - 2x = -9
-2x = - 30
x = 15

(fog)⁻¹ (-9) = 15

f(x) = 2x + 3
g(x)= 9 - x

fog(x)= f { g(x)} 
(fog)(x) = f (9 -x)
(fog)(x) =  2 (9-x) + 3
(fog)(x) = 18 - 2x + 3
(fog)(x) = 21 - 2x

(fog)⁻¹ (21 - 2x) = x
21 - 2x = -9
-2x = - 30
x = 15