Tap the blue circles to see an explanation.
$$ \begin{aligned}(x^2+4x+3)(x^2+9x+20)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}x^4+13x^3+59x^2+107x+60\end{aligned} $$ | |
① | Multiply each term of $ \left( \color{blue}{x^2+4x+3}\right) $ by each term in $ \left( x^2+9x+20\right) $. $$ \left( \color{blue}{x^2+4x+3}\right) \cdot \left( x^2+9x+20\right) = x^4+9x^3+20x^2+4x^3+36x^2+80x+3x^2+27x+60 $$ |
② | Combine like terms: $$ x^4+ \color{blue}{9x^3} + \color{red}{20x^2} + \color{blue}{4x^3} + \color{green}{36x^2} + \color{orange}{80x} + \color{green}{3x^2} + \color{orange}{27x} +60 = \\ = x^4+ \color{blue}{13x^3} + \color{green}{59x^2} + \color{orange}{107x} +60 $$ |