Question

example 6

1. many cell phone plans have an option to include more than one phone. the function for the monthly cost of cell phone service from a wireless company is f(x)=25x + 200, where x is the number of phones on the plan. find and interpret f(3) and f(5).

Explanation:

Step1: Find f(3)

Substitute x = 3 into f(x)=25x + 200. So f(3)=25×3+200.
$f(3)=75 + 200=275$.

Step2: Interpret f(3)

The monthly cost of having 3 phones on the plan is $275.

Step3: Find f(5)

Substitute x = 5 into f(x)=25x + 200. So f(5)=25×5+200.
$f(5)=125+200 = 325$.

Step4: Interpret f(5)

The monthly cost of having 5 phones on the plan is $325.

Answer:

f(3) = 275, which means the monthly cost of having 3 phones on the plan is $275. f(5)=325, which means the monthly cost of having 5 phones on the plan is $325.