Tap the blue circles to see an explanation.
$$ \begin{aligned}-7x^2(3x^3-4x^2+6x+2)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-(21x^5-28x^4+42x^3+14x^2) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-21x^5+28x^4-42x^3-14x^2\end{aligned} $$ | |
① | Multiply $ \color{blue}{7x^2} $ by $ \left( 3x^3-4x^2+6x+2\right) $ $$ \color{blue}{7x^2} \cdot \left( 3x^3-4x^2+6x+2\right) = 21x^5-28x^4+42x^3+14x^2 $$ |
② | Remove the parentheses by changing the sign of each term within them. $$ - \left(21x^5-28x^4+42x^3+14x^2 \right) = -21x^5+28x^4-42x^3-14x^2 $$ |