| $$ \begin{aligned}\frac{x^2+10+25}{x^2-3x-40}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{x^2+35}{x^2-3x-40}\end{aligned} $$ | |
| ① | Simplify numerator $$ x^2+ \color{blue}{10} + \color{blue}{25} = x^2+ \color{blue}{35} $$ |