di ketahui f(x) = 1-2x dan (g°f) (x) = 4x²-6x+3 tentukan fungsi g(x) dan nilai (f°g) (4)

jawab

gof(x) = 4x² - 6x + 3
g{f(x)} = 4x²  -6x + 3
g(1- 2x) = 4x² -6x + 3
g(x) = 4 (1- x)/2)² - 6 { (1- x)/2 } + 3
g(x)= 4 (1/4)(1-2x+x²)  - 3(1 - x)  + 3
g(x) = 1 - 2x + x² - 3 + 3x + 3
g(x)= x² + x + 1

fog(4) = f { g(4)} = f (4²+ 4 +1)
= f(21) 
= 1 - 2(21)
= 1 - 42
= - 41