diketahui f(x)=x+2 dan g(x)=x kuadrat -7x+6.jika (f o g)(a)=(g o f)(a),nilai a adlah...

jawab

fog(a) = gof(a)
f{ g(a)} = g{f(a)}
f(a²-7a +6) =  g(a+2)
(a² -7a + 6) + 2 = (a+2)² -7(a+2) + 6
a² -7a + 8 = a² + 4a +4 -7a -14 + 6
a² -7a + 8 = a² - 3a  - 4
-7a + 8 = -3a - 4
-7a + 3a = -4 - 8
-4a = -12
a = 3