Finding outputs of a two-step function

Introduction

In this lesson, we have two-step functions with decimals modeling real world problems. In such a case we find outputs of those functions.

Example 1

The amount that Jane has is given by the function Ax = 0.8x + 18, where x is her allowance in dollars. What is the amount she has if her allowance is $15?

Solution

Step 1:

Amount with Jane, Ax = 0.8x + 18;x=15

Step 2:

Ax = 0.8x + 18=0.8(15)+18 = 12.0+18 = $30

So, Ax = $30

Example 2

The sum of three consecutive numbers is given by the function Sn = 3n + 3 where n is the smallest number. If the smallest of the three numbers is 38 what is the sum of the three consecutive numbers?

Solution

Step 1:

Sum of numbers, Sn = 3n + 3; n = 38

Step 2:

Sn = 3n + 3 = 338 + 3 = 114 + 3 = 117

So, S38 = 117