At one gym, there is a $12 start-up fee, and after that each month at the gym costs $20. At another gym, it costs $4 to startup, but after that, each month at the gym costs $22. After how many months will the cost of both gyms be thge same?

Respuesta :

Answer:

In 4 months the cost of both gyms will be the same.

Step-by-step explanation:

At first we need to model the function to calculate the cost of the 2 gyms.

Slope-intercept equation of linear function

[tex]f(x)=mx+b[/tex]

where

[tex]m\rightarrow[/tex] slope of line

[tex]b\rightarrow[/tex] y-intercept

Let linear function to calculate total cost of gym be:

[tex]c(n)=mn+b[/tex]

where

[tex]c\rightarrow[/tex] total cost of gym

[tex]m\rightarrow[/tex] cost per month (slope)

[tex]n\rightarrow[/tex] number of months

[tex]b\rightarrow[/tex] start-up fee (y-intercept)

For Gym 1

[tex]m=20[/tex] , [tex]b=12[/tex]

[tex]c(n)=20n+12[/tex]

For Gym 2

[tex]m=22[/tex] , [tex]b=4[/tex]

[tex]c(n)=22n+4[/tex]

In order to find the number of months the cost of both gyms will be the same, we need to equate both functions and solve for number of months [tex](n)[/tex]

[tex]20n+12=22n+4[/tex]

[tex]\\\textrm{Subtracting 22n from both sides}\\20n-22n+12=22n-22n+4\\-2n+12=4\\\textrm{Subtracting 12 from both sides}\\-2n+12-12=4-12\\-2n=-8\\\textrm{Dividing both sides by -2}\\\frac{-2}{-2}n=\frac{-8}{-2}\\n=4\textrm{ months}[/tex]

So,

In 4 months the cost of both gyms will be the same.