jika f(x) = x²–5x+1 dan (f°g)(x)=4x²+2x–5, maka g(3–4x)=....

f (x) = x^2 -5x + 1 dan ( f o g )(x) = 4x^2 +2x -5
f o g (x) = 4x^2 +2x - 5
f { g(x) } = 4x^2 + 2x -5
{ g(x) }^2 - 5.g(x) + 1 = 4x^2 + 2x -5
{ g(x) - 5/2 }^2 - (5/2)^2 + 1 = 4x^2 +2x -5
{ g(x) - 5/2 }^2 = 4x^2 +2x -5 + 5/2
{ g(x) - 5/2 }^2 = 4x^2 +2x - 5/2
g(x) - 5/2 = √( 4x^2 +2x -5/2)
g (x) = √(4x^2 +2x -5/2) + 5/2
g ( 3-x) =√{ 4(3-x)^2 +2(3-x) -5/2 } + 5/2
= √{ 36-24x+4x^2 + 6 - 2x -5/2 } + 5/2
= √{4x^2 -26x +42 - 5/2} + 5/2
= √{ 4x^2 -26x + 39 1/2 } + 5/2