Question

Given that f(x) = x² + 6x and g(x) = x + 9 calculate
a) f•g (4) =
B) g•f (4) =

Answer 1

247

49

Explanation:

a) f•g (4) =

f•g (x) = f(g(x)) = (x + 9)^2 + 6(x + 9)

f•g (4) = (4 + 9)^2 + 6(4 + 9)

= 13^2 + 6(13)

= 247

B) g•f (4) =

g•f (x) = g(f(x)) = x^2 + 6x + 9

g•f (4) = 4^2 + 6(4) + 9

= 16 + 24 + 9

= 49