F (x) = x^2-4x+2 dan g(x)=3x-7 Tentukan : f komposisi g g komposisi f (5)

f(x) = x² - 4x + 2
g(x) = 3x - 7
f o g
= f [g(x)]
= f (3x - 7)
= (3x - 7)² - 4(3x - 7) + 2
= 9x² - 42x + 49 - 12x + 28 + 2
= 9x² - 54x + 79

g [f(5)]
= g ( 5² - 4(5) + 2)
= g ( 25 - 20 + 2)
= g (7)
= 3(7) - 7
= 21 - 7
= 14

a).
(f ○ g)(x)
= f(g(x))
= f(3x - 7)
= (3x - 7)^2 - 4(3x - 7) + 2
= 9x^2 - 42x + 49 - 12x + 28 + 2
= 9x^2 - 54x + 79

b).
(g ○ f)(x)
= g(f(x))
= 3(x^2 - 4x + 2) - 7
= 3x^2 - 12x + 6 - 7
= 3x^2 - 12x - 1

(g ○ f)(5)
= 3(5)^2 - 12(5) - 1
= 75 - 60 - 1
= 14