| $$ \begin{aligned}x^0+x^3+x^4+x^5+x^7& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}x^7+x^5+x^4+x^3+1\end{aligned} $$ | |
| ① | Combine like terms: $$ x^7+x^5+x^4+x^3+1 = x^7+x^5+x^4+x^3+1 $$ |