Tap the blue circles to see an explanation.
| $$ \begin{aligned}\frac{3x-9}{12-4x}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{3}{-4} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-\frac{3}{4}\end{aligned} $$ | |
| ① | Simplify $ \dfrac{3x-9}{12-4x} $ to $ \dfrac{3}{-4} $. Factor both the denominator and the numerator, then cancel the common factor. $\color{blue}{x-3}$. $$ \begin{aligned} \frac{3x-9}{12-4x} & =\frac{ 3 \cdot \color{blue}{ \left( x-3 \right) }}{ \left( -4 \right) \cdot \color{blue}{ \left( x-3 \right) }} = \\[1ex] &= \frac{3}{-4} \end{aligned} $$ |
| ② | Place minus sign in front of the fraction. |