Tap the blue circles to see an explanation.
$$ \begin{aligned}(2x-a)^4& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} \htmlClass{explanationCircle explanationCircle4}{\textcircled {4}} } }}}a^4-8a^3x+24a^2x^2-32ax^3+16x^4\end{aligned} $$ | |
① | $$ (2x-a)^4 = (2x-a)^2 \cdot (2x-a)^2 $$ |
② | Find $ \left(2x-a\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}{ a }$. $$ \begin{aligned}\left(2x-a\right)^2 = \color{blue}{\left( 2x \right)^2} -2 \cdot 2x \cdot a + \color{red}{a^2} = 4x^2-4ax+a^2\end{aligned} $$ |
③ | Multiply each term of $ \left( \color{blue}{4x^2-4ax+a^2}\right) $ by each term in $ \left( 4x^2-4ax+a^2\right) $. $$ \left( \color{blue}{4x^2-4ax+a^2}\right) \cdot \left( 4x^2-4ax+a^2\right) = \\ = 16x^4-16ax^3+4a^2x^2-16ax^3+16a^2x^2-4a^3x+4a^2x^2-4a^3x+a^4 $$ |
④ | Combine like terms: $$ 16x^4 \color{blue}{-16ax^3} + \color{red}{4a^2x^2} \color{blue}{-16ax^3} + \color{green}{16a^2x^2} \color{orange}{-4a^3x} + \color{green}{4a^2x^2} \color{orange}{-4a^3x} +a^4 = \\ = a^4 \color{orange}{-8a^3x} + \color{green}{24a^2x^2} \color{blue}{-32ax^3} +16x^4 $$ |