minta tolong dong master nim

g(x) = x - 2
g^-1 (x) = x + 2

(fog)(x) = F(x) = 2x² - 8x - 11

f(x) = F(g^-1 (x))
f(x) = 2(x + 2)² - 8(x + 2) - 11
f(x) = 2(x² + 4x + 4) - 8x - 16 - 11
f(x) = 2x² - 19

(fog)(3) = 2.3² - 8.3 - 11
(fog)(3) = 18 - 24 - 11 = -17

(fog)(a) = 5
2a² - 8a - 11 = 5
2a² - 8a - 16 = 0
a² - 4a - 8 = 0 ---> rumus abc
a1.2 = (4 ± 4√3)/2
a1.2 = 2 ± 2√3

Nilai a yg memenuhi :
a = 2 + 2√3
atau
a = 2 - 2√3