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Factor \(\displaystyle - 63 x^{3} - 42 x^{2} + 63 x + 42\).
Factoring out the GCF \(\displaystyle -21\) from each term gives \(\displaystyle -21(3 x^{3} + 2 x^{2} - 3 x - 2)\). Grouping the first two terms and factoring out their GCF, \(\displaystyle x^{2}\), gives \(\displaystyle x^{2}(3 x + 2)\). Grouping the last two terms and factoring out their GCF, \(\displaystyle -1\), gives \(\displaystyle -1(3 x + 2)\). The polynomial now has a common binomial factor of \(\displaystyle 3 x + 2\). This gives \(\displaystyle -21[x^{2} \left(3 x + 2\right) -1 \cdot \left(3 x + 2\right)] = -21\left(3 x + 2\right) \left(x^{2} - 1\right)\). The quadratic factor can be factored using the difference of squares to give \(\displaystyle -21\left(x - 1\right) \left(x + 1\right) \left(3 x + 2\right). \)
\begin{question}Factor $- 63 x^{3} - 42 x^{2} + 63 x + 42$.
\soln{9cm}{Factoring out the GCF $-21$ from each term gives $-21(3 x^{3} + 2 x^{2} - 3 x - 2)$. Grouping the first two terms and factoring out their GCF, $x^{2}$, gives $x^{2}(3 x + 2)$. Grouping the last two terms and factoring out their GCF, $-1$, gives $-1(3 x + 2)$. The polynomial now has a common binomial factor of $3 x + 2$. This gives $-21[x^{2} \left(3 x + 2\right) -1 \cdot \left(3 x + 2\right)] = -21\left(3 x + 2\right) \left(x^{2} - 1\right)$. The quadratic factor can be factored using the difference of squares to give $-21\left(x - 1\right) \left(x + 1\right) \left(3 x + 2\right). $}
\end{question}
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\begin{document}\begin{question}(10pts) The question goes here!
\soln{9cm}{The solution goes here.}
\end{question}\end{document}<p> <p>Factor <img class="equation_image" title=" \displaystyle - 63 x^{3} - 42 x^{2} + 63 x + 42 " src="/equation_images/%20%5Cdisplaystyle%20-%2063%20x%5E%7B3%7D%20-%2042%20x%5E%7B2%7D%20%2B%2063%20x%20%2B%2042%20" alt="LaTeX: \displaystyle - 63 x^{3} - 42 x^{2} + 63 x + 42 " data-equation-content=" \displaystyle - 63 x^{3} - 42 x^{2} + 63 x + 42 " /> . </p> </p><p> <p>Factoring out the GCF <img class="equation_image" title=" \displaystyle -21 " src="/equation_images/%20%5Cdisplaystyle%20-21%20" alt="LaTeX: \displaystyle -21 " data-equation-content=" \displaystyle -21 " /> from each term gives <img class="equation_image" title=" \displaystyle -21(3 x^{3} + 2 x^{2} - 3 x - 2) " src="/equation_images/%20%5Cdisplaystyle%20-21%283%20x%5E%7B3%7D%20%2B%202%20x%5E%7B2%7D%20-%203%20x%20-%202%29%20" alt="LaTeX: \displaystyle -21(3 x^{3} + 2 x^{2} - 3 x - 2) " data-equation-content=" \displaystyle -21(3 x^{3} + 2 x^{2} - 3 x - 2) " /> . Grouping the first two terms and factoring out their GCF, <img class="equation_image" title=" \displaystyle x^{2} " src="/equation_images/%20%5Cdisplaystyle%20x%5E%7B2%7D%20" alt="LaTeX: \displaystyle x^{2} " data-equation-content=" \displaystyle x^{2} " /> , gives <img class="equation_image" title=" \displaystyle x^{2}(3 x + 2) " src="/equation_images/%20%5Cdisplaystyle%20x%5E%7B2%7D%283%20x%20%2B%202%29%20" alt="LaTeX: \displaystyle x^{2}(3 x + 2) " data-equation-content=" \displaystyle x^{2}(3 x + 2) " /> . Grouping the last two terms and factoring out their GCF, <img class="equation_image" title=" \displaystyle -1 " src="/equation_images/%20%5Cdisplaystyle%20-1%20" alt="LaTeX: \displaystyle -1 " data-equation-content=" \displaystyle -1 " /> , gives <img class="equation_image" title=" \displaystyle -1(3 x + 2) " src="/equation_images/%20%5Cdisplaystyle%20-1%283%20x%20%2B%202%29%20" alt="LaTeX: \displaystyle -1(3 x + 2) " data-equation-content=" \displaystyle -1(3 x + 2) " /> . The polynomial now has a common binomial factor of <img class="equation_image" title=" \displaystyle 3 x + 2 " src="/equation_images/%20%5Cdisplaystyle%203%20x%20%2B%202%20" alt="LaTeX: \displaystyle 3 x + 2 " data-equation-content=" \displaystyle 3 x + 2 " /> . This gives <img class="equation_image" title=" \displaystyle -21[x^{2} \left(3 x + 2\right) -1 \cdot \left(3 x + 2\right)] = -21\left(3 x + 2\right) \left(x^{2} - 1\right) " src="/equation_images/%20%5Cdisplaystyle%20-21%5Bx%5E%7B2%7D%20%5Cleft%283%20x%20%2B%202%5Cright%29%20-1%20%5Ccdot%20%5Cleft%283%20x%20%2B%202%5Cright%29%5D%20%3D%20-21%5Cleft%283%20x%20%2B%202%5Cright%29%20%5Cleft%28x%5E%7B2%7D%20-%201%5Cright%29%20" alt="LaTeX: \displaystyle -21[x^{2} \left(3 x + 2\right) -1 \cdot \left(3 x + 2\right)] = -21\left(3 x + 2\right) \left(x^{2} - 1\right) " data-equation-content=" \displaystyle -21[x^{2} \left(3 x + 2\right) -1 \cdot \left(3 x + 2\right)] = -21\left(3 x + 2\right) \left(x^{2} - 1\right) " /> . The quadratic factor can be factored using the difference of squares to give <img class="equation_image" title=" \displaystyle -21\left(x - 1\right) \left(x + 1\right) \left(3 x + 2\right). " src="/equation_images/%20%5Cdisplaystyle%20-21%5Cleft%28x%20-%201%5Cright%29%20%5Cleft%28x%20%2B%201%5Cright%29%20%5Cleft%283%20x%20%2B%202%5Cright%29.%20%20" alt="LaTeX: \displaystyle -21\left(x - 1\right) \left(x + 1\right) \left(3 x + 2\right). " data-equation-content=" \displaystyle -21\left(x - 1\right) \left(x + 1\right) \left(3 x + 2\right). " /> </p> </p>