Finding outputs of a two-step function with decimals that models a real-world situation

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

The amount that Jane has is given by the function A(x) = 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, A(x) = 0.8x + $18; x = $15

Step 2:

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

So, A(x) = $30

The sum of three consecutive numbers is given by the function S(n) = 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, S(n) = 3n + 3; n = 38

Step 2:

S(n) = 3n + 3 = 3(38) + 3 = 114 + 3 = 117

So, S(38) = 117