| $$ \begin{aligned}\frac{s^3-12s^2+27s}{s-9}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}s^2-3s\end{aligned} $$ | |
| ① | Simplify $ \dfrac{s^3-12s^2+27s}{s-9} $ to $ s^2-3s$. Factor both the denominator and the numerator, then cancel the common factor. $\color{blue}{s-9}$. $$ \begin{aligned} \frac{s^3-12s^2+27s}{s-9} & =\frac{ \left( s^2-3s \right) \cdot \color{blue}{ \left( s-9 \right) }}{ 1 \cdot \color{blue}{ \left( s-9 \right) }} = \\[1ex] &= \frac{s^2-3s}{1} =s^2-3s \end{aligned} $$ |