| $$ \begin{aligned}3x^2+5x+4x^2-2x& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}7x^2+3x\end{aligned} $$ | |
| ① | Combine like terms: $$ \color{blue}{3x^2} + \color{red}{5x} + \color{blue}{4x^2} \color{red}{-2x} = \color{blue}{7x^2} + \color{red}{3x} $$ |