Question
Answer
$$\dfrac{r-3}{r^2+4r-21}=\dfrac{1}{r+7}$$
Explanation
| $$ \begin{aligned}\frac{r-3}{r^2+4r-21}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{1}{r+7}\end{aligned} $$ | |
| ① | Simplify $ \dfrac{r-3}{r^2+4r-21} $ to $ \dfrac{1}{r+7} $. Factor both the denominator and the numerator, then cancel the common factor. $\color{blue}{r-3}$. $$ \begin{aligned} \frac{r-3}{r^2+4r-21} & =\frac{ 1 \cdot \color{blue}{ \left( r-3 \right) }}{ \left( r+7 \right) \cdot \color{blue}{ \left( r-3 \right) }} = \\[1ex] &= \frac{1}{r+7} \end{aligned} $$ |
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Simplify Rational Expressions