| $$ \begin{aligned}\frac{2x^2-10x}{x^2-25}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{2x}{x+5}\end{aligned} $$ | |
| ① | Simplify $ \dfrac{2x^2-10x}{x^2-25} $ to $ \dfrac{2x}{x+5} $. Factor both the denominator and the numerator, then cancel the common factor. $\color{blue}{x-5}$. $$ \begin{aligned} \frac{2x^2-10x}{x^2-25} & =\frac{ 2x \cdot \color{blue}{ \left( x-5 \right) }}{ \left( x+5 \right) \cdot \color{blue}{ \left( x-5 \right) }} = \\[1ex] &= \frac{2x}{x+5} \end{aligned} $$ |