Question

Diketahui f(x)= 2x+1 dan fog(x+1)= -2x²-4x-1
Tentukan nilai g(-2) !

Answer 1

(fog) (x+1)= -2x²-4x-1
2g(x) + 1 = -2(x-1)²-4(x-1)-1
g(x) = -2(x-1)²-4(x-1)-2 bagi 2
g(-2)=-2(-2-1)²-4(-2-1) - 2 bagi 2
= -2(-3)² - 4(-3)-2 bagi 2
= -18+12-2 bagi 2
= -8 / 2
=-4

Answer 2

F o g = f(g(x))
f(g(x)) = -2x² - 4x -1
2(g(x)) +1 =-2x²-4x-1
G(x) = (-2x²-4x-2)/2
= -x²-2x-1
G(-2)=-(-2²)-2(-2)-1
= -4+4-1
=–1