Factor polynomial $$ 3x^{3}-x^{2}-21x+7 $$
Answer
$$ 3x^{3}-x^{2}-21x+7 = ( x^{2}-7 )( 3x-1 ) $$
Explanation
To factor $ 3x^{3}-x^{2}-21x+7 $ we can use factoring by grouping:
Group $ \color{blue}{ 3x^{3} }$ with $ \color{blue}{ -x^{2} }$ and $ \color{red}{ -21x }$ with $ \color{red}{ 7 }$ then factor each group.
$$ \begin{aligned} 3x^{3}-x^{2}-21x+7 = ( \color{blue}{ 3x^{3}-x^{2} } ) + ( \color{red}{ -21x+7 }) &= \\ &= \color{blue}{ x^{2}( 3x-1 )} + \color{red}{ -7( 3x-1 ) } = \\ &= (x^{2}-7)(3x-1) \end{aligned} $$This page was created using
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