| $$ \begin{aligned}x^1+x^7+x^8+x^9+x^{10}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}x^{10}+x^9+x^8+x^7+x\end{aligned} $$ | |
| ① | Combine like terms: $$ x^{10}+x^9+x^8+x^7+x = x^{10}+x^9+x^8+x^7+x $$ |