plot (1-.9^x)/(1-.8^x),0.5,((1-.9^x)/.9^x)/((1-.8^x)/(.8^x)) from x=1 to x=30

Uh oh! Wolfram|Alpha doesn't run without JavaScript.

Please enable JavaScript. If you don't know how, you can find instructionshere.Once you've done that, refresh this page to start using Wolfram|Alpha.