diketahui f(x) = x+5 dan g(x) = [tex] \frac{x - 1}{x²+2x - 3} [/tex] . jika (g o f)(a) = [tex] \frac{1}{6} [/tex] , nilai a adalah

gof(a) = 1/6
g(f(a)) = 1/6
g(a +5) = 1/6

g(x)
= (x-1) / (x² + 2x - 3)
= (x-1) / (x + 3)(x - 1)
= 1/(x + 3)

g(a + 5) = 1/6
1/(a+5+3) = 1/6
1/(a + 8) = 1/6

a + 8 = 6
a = -2