| $$ \begin{aligned}\frac{x^2+2x-8}{x^2+11x+28}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{x-2}{x+7}\end{aligned} $$ | |
| ① | Simplify $ \dfrac{x^2+2x-8}{x^2+11x+28} $ to $ \dfrac{x-2}{x+7} $. Factor both the denominator and the numerator, then cancel the common factor. $\color{blue}{x+4}$. $$ \begin{aligned} \frac{x^2+2x-8}{x^2+11x+28} & =\frac{ \left( x-2 \right) \cdot \color{blue}{ \left( x+4 \right) }}{ \left( x+7 \right) \cdot \color{blue}{ \left( x+4 \right) }} = \\[1ex] &= \frac{x-2}{x+7} \end{aligned} $$ |