Diketahui

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f(x) = x + 2
dan
g(x) = x {}^{2}  - 7x + b
jika
(f.g)(a) = (g.f)(a)
nilai
a :  = .....
tentukan
(f.g)(x) = ...  \ (g.f)(x) = ...

Diketahui

Berarti :
a² -7a + b + 2 = (a+2)² -7(a+2) +b
a² -7a + b + 2 = a²+4a+4-7a-14+b
a²-7a + b + 2 = a²-3a-10+b
a²-a² -7a+3a +b -b + 2+10 = 0
-4a +12 = 0
-4a = -12
a = -12/-4
a = 3
jadi a = 3