Question

Given the functions a(x) = 3x − 12 and b(x) = x − 9, solve a[b(x)] and select the correct answer below.

Answer 1

the choices are
a[b(x)] = 3x2 − 21
a[b(x)] = 3x2 − 39
a[b(x)] = 3x − 21
a[b(x)] = 3x − 39

Answer 2

basically, you want to take b(x) and substitute it for x in the expression a(x) = 3(x) - 12

a(x) = 3x-12
a(b(x)) = 3*(b(x)) - 12 = 3(x-9) - 12