Question

Dik G(X) = 2x - 1 dan (fog)(x) = 4x² - 6x + 10. Nilai f(3) = ...

Answer 1

(fog)(x) = 4x² - 6x + 10
f(2x - 1) = 4x² - 6x + 10

misal y=2x-1
2x = y+1 ⇒ 

f(y) = 4((y+1)/2)² - 6((y+1)/2) + 10
=4((y²+2y+1)/4) - 3(y+1) + 10
=y²+2y+1-3y-3+10
=y²-y+8

f(x)=x²-x+8
f(3)=3²-3+8=14

Answer 2

 (fog)(x) = 4x² - 6x + 10
 f(g(x)) = 4x² - 6x + 10
f(2x - 1) = 4x² - 6x + 10

misal g(x) => t = 2x - 1
                        x = (t-1)/2
f((t-1)/2) = 4((t-1)/2)² - 6((t-1)/2) + 10
                = t²-2t+1 -3t + 3 + 10
                = t² - 5t + 14
f(x) = t² - 5t + 14
f(3) = (3)² - 5(3) + 14
       = 9 - 15 + 14
       = 8