| $$ \begin{aligned}\frac{x^2-15x+56}{x^2-16x+63}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{x-8}{x-9}\end{aligned} $$ | |
| ① | Simplify $ \dfrac{x^2-15x+56}{x^2-16x+63} $ to $ \dfrac{x-8}{x-9} $. Factor both the denominator and the numerator, then cancel the common factor. $\color{blue}{x-7}$. $$ \begin{aligned} \frac{x^2-15x+56}{x^2-16x+63} & =\frac{ \left( x-8 \right) \cdot \color{blue}{ \left( x-7 \right) }}{ \left( x-9 \right) \cdot \color{blue}{ \left( x-7 \right) }} = \\[1ex] &= \frac{x-8}{x-9} \end{aligned} $$ |