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