Trong khai triển nhị thức <span class="MathJax_Preview" style="color: inherit;"><span class="MJXp-math" id="MJXp-Span-1"><span class="MJXp-mstyle" id="MJXp-Span-2"><span class="MJXp-mo" id="MJXp-Span-3" style="margin-left: 0em; margin-right: 0em;">(</span><span class="MJXp-mi MJXp-italic" id="MJXp-Span-4">a</span><span class="MJXp-mo" id="MJXp-Span-5" style="margin-left: 0.267em; margin-right: 0.267em;">+</span><span class="MJXp-mn" id="MJXp-Span-6">2</span><span class="MJXp-msubsup" id="MJXp-Span-7"><span class="MJXp-mo" id="MJXp-Span-8" style="margin-left: 0em; margin-right: 0.05em;">)</span><span class="MJXp-mrow MJXp-script" id="MJXp-Span-9" style="vertical-align: 0.5em;"><span class="MJXp-mi MJXp-italic" id="MJXp-Span-10">n</span><span class="MJXp-mo" id="MJXp-Span-11">+</span><span class="MJXp-mn" id="MJXp-Span-12">7</span></span></span><span class="MJXp-mo" id="MJXp-Span-13" style="margin-left: 0em; margin-right: 0em;">(</span><span class="MJXp-mi MJXp-italic" id="MJXp-Span-14">n</span><span class="MJXp-mo" id="MJXp-Span-15" style="margin-left: 0.333em; margin-right: 0.333em;">∈</span><span class="MJXp-mrow" id="MJXp-Span-16"><span class="MJXp-mi undefined" id="MJXp-Span-17">N</span></span><span class="MJXp-mo" id="MJXp-Span-18" style="margin-left: 0em; margin-right: 0em;">)</span></span></span></span><span id="MathJax-Element-1-Frame" class="mjx-chtml MathJax_CHTML MJXc-processing" tabindex="0" style="font-size: 127%;"></span><script type="math/tex" id="MathJax-Element-1">\Large (a+2)^{n+7}(n \in \mathbb N)</script> có tất