Visual proof why a+ar+ar²+… = a/(1-r), for |r|<1 Posted on 2020/07/27 by Carl Robitaille Here's a visual proof why a+ar+ar²+… = a/(1-r), for |r|<1 pic.twitter.com/Sg1hGYuHEI— Fermat's Library (@fermatslibrary) July 27, 2020