Question

Diketahui fungsi f:R-->R dengan f(x)= x^{2} -4x+2 dan fungsi g:R-->R dengan g(x)=3x-7 tentukan:
a.(g o f )(x)
b.(f o g)(x)
c.(g o f)(5)
d.(f o g)(10)
yang bisa bantu jawab !

Answer 1

A. (gof)(x) = g(f(x))
= g(x²-4x+2)
= 3(x²-4x+2) -7
= 3x² -12x+6 -7
= 3x²-12x -1

b. (fog)(x) = f(g(x))
= f(3x-7)
=(3x-7)² - 4(3x-7)+2
=9x²-42x+49-12x+28+2
=9x²-54x+79

c. (gof)(5)
(gof)(x) = 3x²-12x -1
(gof)(5) = 3(5)² -12(5) -1
= 3*25 - 60-1
= 14

d. (fog)(10)
(fog)(x) = 9x²-16x+79
(fog)(10) = 9(10)² - 54(10) +79
=9*100 -540+79
= 900-540+79
=439