Question

the graph below shows the total cost of using a music provider for one month depending on how many songs were downloaded.

Answer 1

Use the graph to find the equation for the total cost in terms of number of songs

1. Find the slope (m): Use the ordered pair of two points in the next formula:

$m=\frac{y_2-y_1}{x_2-x_1}$$m=\frac{18-15}{2-0}=\frac{3}{2}$

2. Identify the y-intercept: Value of y when x is 0

y intercept (b): 15

3. Use the slope and y-intercept to write the equation of the line:

$\begin{gathered} y=mx+b \\ \\ y=\frac{3}{2}x+15 \end{gathered}$

___________

If Jeremaine downloads 75 songs in one month (x=75), to find the total cost evaluate the function for x=75:

$\begin{gathered} y=\frac{3}{2}(75)+15 \\ \\ y=112.5+15 \\ \\ y=127.5 \end{gathered}$Then, the total cost for the month is $127.50