| $$ \begin{aligned}2z^2+z^2+10z& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}3z^2+10z\end{aligned} $$ | |
| ① | Combine like terms: $$ \color{blue}{2z^2} + \color{blue}{z^2} +10z = \color{blue}{3z^2} +10z $$ |