Question

Dik :f(x) = x ^2 -4x +2
g(x)= 3x-7

dit : a. (gof) (x)
b. (fog) (x)
c. (gof) (5)
d. (fog) (10)

Answer 1

A. (gof)(x) = g(f(x)) = 3(x²-4x+2) - 7 = 3x²-12x+6-7 = 3x²-12x-1
b. (fog) (x) = f(g(x)) = (3x-7)²-4(3x-7)+2 = 9x²-42x+49-12x+28+2 = 9x²-54x+79
c. (gof) (5) = 3(5)²-12(5)-1 = 75-60-1 = 14
d. (fog) (10) = 9(10)²-54(10)+79 = 439

Semoga Bermanfaat :) 

Answer 2

A. (g°f) (x) = g(f(x)) = 3.f(x)-7
= 3(x^2-4x+2)-7
= 3x^2-12x+6-7
= 3x^2-12x-1
b. (f°g) (x) = f(g(x)) = (3x-2)^2-4(3x-2)+2
= (3x-2)(3x-2)-12x+8+2
= 9x^2-12x+4-12x+10
= 9x^2-24x+14
c. (g°f) (5) = 3x^2-12x-1
= 3(5^2)-12(5)-1
=3(25)-60-1
=75-61
= 14
d. (f°g) (10) = 9x^2-24x+14
= 9(10^2)-24(10)+14
= 9(100)-240+14
= 900-226
= 674