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