Question

Let f(x) = 9x − 1 and g(x) = 3x + 1. Find the following.

(a) (f + g)(−2) =

(b) (f/g)(3) =

(c) (f − g)(0) =

(d) (f · g)(2) =

Answer 1

(a) -24

(b) 2.6

(c) -2

(d) 119

Explanation:

It is convenient to let a calculator or spreadsheet do the function evaluations. That makes the composite functions easier to calculate.

(a) (f+g)(-2) = f(-2) +g(-2) = -19 +(-5) = -24

(b) (f/g)(3) = f(3)/g(3) = 26/10 = 2.6

(c) (f-g)(0) = f(0) -g(0) = -1 -1 = -2

(d) (f·g)(2) = f(2)·g(2) = 17·7 = 119