For the pair of functions fx x 3 and gx x2 x 6 find the
For the pair of functions, f(x) = x + 3 and g(x) = x^2 + x - 6, find the following. (f g)(x) (f g)(2) (g f)(x) (g f)(2) (f g)(x) (Simplify your answer.)
Solution
Given f(x) = x+3
g(x) = x2+x-6
a)(fog)(x):
(fog)(x) = f(g(x))
= f(x2+x-6)
f(x) = x+3
f(x2+x-6) = x2+x-6 +3
= x2+x-3
Therefore, (fog)(x)=x2+x-3
b) (fog)(2):
(fog)(x)=x2+x-3
(fog)(2)= 22+2-3
= 4+2-3
= 3
Therefore, (fog)(2) = 3
c)(gof)(x):
(gof)(x) = g(f(x))
= g(x+3)
g(x) = x2+x-6
g(x+3) = (x+3)2+(x+3)-6
= x2+32+6x+x+3-6
= x2+7x+6
Therefore, (gof)(x) = x2+7x+6
d) (gof)(2):
(gof)(x) = x2+7x+6
(gof)(2) = 22+7(2)+6
= 4+14+6
= 24
Therefore, (gof)(2) = 24

