Tap the blue circles to see an explanation.
| $$ \begin{aligned}3x-(2x-4)^2& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}3x-(4x^2-16x+16) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}3x-4x^2+16x-16 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}-4x^2+19x-16\end{aligned} $$ | |
| ① | Find $ \left(2x-4\right)^2 $ using formula. $$ (A - B)^2 = \color{blue}{A^2} - 2 \cdot A \cdot B + \color{red}{B^2} $$where $ A = \color{blue}{ 2x } $ and $ B = \color{red}{ 4 }$. $$ \begin{aligned}\left(2x-4\right)^2 = \color{blue}{\left( 2x \right)^2} -2 \cdot 2x \cdot 4 + \color{red}{4^2} = 4x^2-16x+16\end{aligned} $$ |
| ② | Remove the parentheses by changing the sign of each term within them. $$ - \left( 4x^2-16x+16 \right) = -4x^2+16x-16 $$ |
| ③ | Combine like terms: $$ \color{blue}{3x} -4x^2+ \color{blue}{16x} -16 = -4x^2+ \color{blue}{19x} -16 $$ |