Diketahui f : x -> 2x + 5 dan f(g(x)) = 13 - 2x. Jika g(f (a^2 + 1)) = 5a - 6 , nilai a sama dengan . . . . . bantu aku ya

f(x) = 2x + 5
f(g(x)) = 13 - 2x
2g(x) + 5 = 13 - 2x
2g(x) = 13 - 2x -5
2g(x) = 8 - 2x
g(x) = (8 - 2x) ÷ 2
g(x) = 4 - x
f(x) = 2x + 5
f(a²+1) = 2(a²+1) + 5
f(a²+1) = 2a²+ 2 + 5
f(a²+1) = 2a² + 7
g(f(a²+1)) = 5a - 6
4 - (2a²+7) = 5a - 6
-2a²-3 = 5a - 6
2a² + 5a + 3 - 6 = 0
2a² + 5a - 3 = 0
(2a - 1)(a + 3) = 0
2a - 1 = 0
2a = 1
a = ½
a + 3 = 0
a = -3
jadi a = ½ atau a = -3