Diketahui f(x) =x+2 dan g(x) = x²-7x+6. Jika (fog)(a) = (gof)(a) , nilai a =

f(g(a)) = g(f(a))
a² - 7a + 8 = (a + 2)² - 7(a + 2) + 6
a² - 7a + 8 = a² - 3a - 4
3a - 7a = -8 - 4
-4a = -12
a = 3