Question

cell phones 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). f(3) = $ , which is the cost of a cell phone plan with phones for month. f(5) = $ , which is the cost of a cell phone plan with phones for month.

Explanation:

Step1: Substitute x = 3 into the function

Substitute \(x = 3\) into \(f(x)=25x + 200\).
\[

$$\begin{align*} f(3)&=25\times3+200\\ &=75 + 200\\ &=275 \end{align*}$$

\]

Step2: Interpret f(3)

\(f(3) = 275\) means the cost of a cell - phone plan with 3 phones for 1 month is $275.

Step3: Substitute x = 5 into the function

Substitute \(x = 5\) into \(f(x)=25x + 200\).
\[

$$\begin{align*} f(5)&=25\times5+200\\ &=125+200\\ &=325 \end{align*}$$

\]

Step4: Interpret f(5)

\(f(5)=325\) means the cost of a cell - phone plan with 5 phones for 1 month is $325.

Answer:

f(3) = $275, which is the cost of a cell phone plan with 3 phones for 1 month;
f(5) = $325, which is the cost of a cell phone plan with 5 phones for 1 month.