Question

A video game club charges a fixed annual membership fee of $18 and $3 per video game rented. Let f(n) represent the total annual cost of renting n video games. Which of the following functions best represents the relationship between f(n) and n if the membership was increased by $20 the next year?

Answer 1

The correct answer is f(n)=3n+38

Explanation:

Put in y=mx+b form, so y= f(n), $3 is fee per video game rented and n is the number of video games rented, b is ($18 fixed fee for this year +$20 fee for next year). So, f(n)=3n+38.

Answer 2

Since there is a flat membership fee of $18, the y intercept is 18. And since there is a $3 fee per number of video games rented, n, the slope or rate of change of the linear equation is 3. The slope-intercept form of a line is:

f(x)=mx+b, where m=slope and b=y-intercept so in terms of n, games rented, the cost, f(n) is:

f(n)=3n+18