Question

Jika g(x)=x-1 dan fog(x)=4×kuadrat-x maka harga f(-2) adalah

Answer 1

Fog(x)=4x^2-x
f(g(X))= 4x^2-x
f(x-1)= 4x^2-x
misal y= x-1
       x= y+1

mka f(x)= 4(x+1)^2-(x+1)
= 4(x^2+2x+1)-x-1
=4X^2+8x+4-x-1
=4x^2+7x+3
jadi f(-2)= 4(-2)^2+7(-2)+3
=16-14+3
=5

Answer 2

G(x) = x - 1 → g'(x) = x + 1
(fog)(x) = 4x² - x

f(x) = ?
= 4(x + 1)² - (x + 1)
= 4(x² + 2x + 1) - x - 1
= 4x² + 8x + 4 - x - 1
= 4x² + 7x + 3

f(-2) = ?
= 4(-2)² + 7(-2) + 3
= 4(4) - 14 + 3
= 16 - 14 + 3
= 5