Tap the blue circles to see an explanation.
$$ \begin{aligned}-3mn(m^2n^3+2mn)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-(3m^3n^4+6m^2n^2) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-3m^3n^4-6m^2n^2\end{aligned} $$ | |
① | Multiply $ \color{blue}{3mn} $ by $ \left( m^2n^3+2mn\right) $ $$ \color{blue}{3mn} \cdot \left( m^2n^3+2mn\right) = 3m^3n^4+6m^2n^2 $$ |
② | Remove the parentheses by changing the sign of each term within them. $$ - \left(3m^3n^4+6m^2n^2 \right) = -3m^3n^4-6m^2n^2 $$ |