| $$ \begin{aligned}6x^2-4x+4x^2+x-1& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}10x^2-3x-1\end{aligned} $$ | |
| ① | Combine like terms: $$ \color{blue}{6x^2} \color{red}{-4x} + \color{blue}{4x^2} + \color{red}{x} -1 = \color{blue}{10x^2} \color{red}{-3x} -1 $$ |