| $$ \begin{aligned}\frac{x^3-4x^2}{x^2-5x+4}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{x^2}{x-1}\end{aligned} $$ | |
| ① | Simplify $ \dfrac{x^3-4x^2}{x^2-5x+4} $ to $ \dfrac{x^2}{x-1} $. Factor both the denominator and the numerator, then cancel the common factor. $\color{blue}{x-4}$. $$ \begin{aligned} \frac{x^3-4x^2}{x^2-5x+4} & =\frac{ x^2 \cdot \color{blue}{ \left( x-4 \right) }}{ \left( x-1 \right) \cdot \color{blue}{ \left( x-4 \right) }} = \\[1ex] &= \frac{x^2}{x-1} \end{aligned} $$ |