Given:
Cost of 1 digital song = $1.05
Cost of 2 digital song = $2.10
Cost of 5 digital song = $5.25
To find:
The equation and the cost of 25 downloaded digital songs.
Solution:
Let us take two points (1, 1.05) and (2, 2.10).
Here [tex]x_1=1, y_1=1.05, x_2=2, y_2=2.10[/tex]
Slope:
[tex]$m=\frac{y_2-y_1}{x_2-x_1}[/tex]
[tex]$m=\frac{2.10-1.05}{2-1}[/tex]
m = 1.05
Using point-slope formula:
[tex]y-y_1=m(x-x_1)[/tex]
[tex]y-1.05=1.05(x-1)[/tex]
[tex]y-1.05=1.05x-1.05[/tex]
Add 1.05 on both sides, we get
[tex]y=1.05x[/tex]
Here x is the independent variable and c is the dependent variable.
So that substitute x = n and y = c.
[tex]c=1.05n[/tex]
The equation is c = 1.05 n.
Substitute n = 25 in the equation.
[tex]c=1.05(25)[/tex]
[tex]c=26.25[/tex]
The cost of 25 songs is $26.25.
