Illustration of the binomial theorem
<a href="//commons.wikimedia.org/wiki/User:Kdkeller" title="User:Kdkeller">Klaus-Dieter Keller</a>, based on <a href="//commons.wikimedia.org/wiki/User:Superm401" class="mw-redirect" title="User:Superm401">User:Superm401</a>
<span class="int-own-work" lang="en">Own work</span>