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