bantuin tolong pliss

g(x) = 2x - 1 dan (f o g) (x) = 2x^2 -8x + 14
f o g (x) = 2x^2 - 8x + 14
f { g(x) } = 2x^2 - 8x + 14
f (2x -1) = 2x^2 - 8x + 14
misal 2x -1 = a
maka 2x = a + 1 => x = (a + 1)/2
f (a) = 2 { (a +1)/2 }^2 - 8(a + 1)/2 + 14
f (a) = 2(a^2 +2a + 1)/4 -4a -4 +14
f (a) = (a^2 +2a + 1)/2 -4a -4 + 14
f (a) = 1/2a^2 - 3a + 21/2
f (x) = 1/2x^2 - 3x + 21/2
y = 1/2x^2 - 3x +21/2
2y = x^2 - 6x + 21
x^2 - 6x = 2y - 21
(x - 3)^2 - 9 = 2y - 21
(x - 3)^2 = 2y - 12
x - 3 = V(2y - 12)
x = V(2y - 12) + 3
f-1(x) = V(2x - 12) + 3
f-1(6) = V(2.6 - 12) + 3
= V(12 - 12) + 3
= V0 + 3
= 3