HOW DO YOU MODEL THE TOTAL COST AS A LINEAR FUNCTION, WITH TIME AS THE INDEPENDENT VARIABLE

Question

THE FORMULA GIVE IS:

F(t) = (pr)t + p

I KNOW THE VALUES OF PR AND R BUT DO NOT UNDERSTAND HOW TO ACTUALLY DO WHAT IS BEING REQUESTED, WHICH IS MODEL THE TOTAL COST AS A LINEAR FUNCTION, WITH TIME AS THE INDEPENDENT VARIABLE.

Answer 1

This is a simple interest formula where p=principal amount and r is the rate. Over time t the principal amount grows to prt+p, so F(t)=p(1+rt). When the constants p and r are replaced by numbers we end up with a linear function. For example, let p=$1000 and r=5% per annum=0.05 then F(t)=1000(1+0.05t)=50t+1000, where t is the number of years and F is the amount or cost after t years.