exponential function help!

[mhagen26]

finding a formula for an exponential function

 

[yoscar04]

What have you tried so far? Have you tried plain substitution? The forum is to help students that get stuck, so please show us what have you done in order to solve your problem.

 

[HallsofIvy]

You want to find 2 values, a and b, and you are given two points, (10, 80) and (30, 20). Setting x= 10, y= 80 in \(\displaystyle y= ab^x\) gives the equation \(\displaystyle 80= a(b^{10})\). Do the same with x= 30, y= 20 to get a second equation so that you have two equations to solve for the two unknowns.

(What happens if you divide one equation by the other?)