Tap the blue circles to see an explanation.
| $$ \begin{aligned}(3x+1)(x+1)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}3x^2+3x+x+1 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}3x^2+4x+1\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{3x+1}\right) $ by each term in $ \left( x+1\right) $. $$ \left( \color{blue}{3x+1}\right) \cdot \left( x+1\right) = 3x^2+3x+x+1 $$ |
| ② | Combine like terms: $$ 3x^2+ \color{blue}{3x} + \color{blue}{x} +1 = 3x^2+ \color{blue}{4x} +1 $$ |