$$ \begin{aligned}1+8x^2-x+6x-7x^2+7& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}x^2+5x+8\end{aligned} $$ | |
① | Combine like terms: $$ \color{blue}{1} + \color{red}{8x^2} \color{green}{-x} + \color{green}{6x} \color{red}{-7x^2} + \color{blue}{7} = \color{red}{x^2} + \color{green}{5x} + \color{blue}{8} $$ |