| $$ \begin{aligned}\frac{9x^2-63x}{7x^3-49x^2}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{9}{7x}\end{aligned} $$ | |
| ① | Simplify $ \dfrac{9x^2-63x}{7x^3-49x^2} $ to $ \dfrac{9}{7x} $. Factor both the denominator and the numerator, then cancel the common factor. $\color{blue}{x^2-7x}$. $$ \begin{aligned} \frac{9x^2-63x}{7x^3-49x^2} & =\frac{ 9 \cdot \color{blue}{ \left( x^2-7x \right) }}{ 7x \cdot \color{blue}{ \left( x^2-7x \right) }} = \\[1ex] &= \frac{9}{7x} \end{aligned} $$ |