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Find the derivative of \(\displaystyle y = (- 7 x^{2} + 5 x + 7)(9 x^{2} - 5 x + 9)(\sin{\left(x \right)})\).
Identifying \(\displaystyle f=- 7 x^{2} + 5 x + 7\) and \(\displaystyle g=\left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)}\) and using the product rule with \(\displaystyle f=- 7 x^{2} + 5 x + 7 \implies f'=5 - 14 x\). This leaves g as \(\displaystyle g = \left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)}\) which also requires the product rule. Pushing down in the new product rule \(\displaystyle f=9 x^{2} - 5 x + 9 \implies f'=18 x - 5\) and \(\displaystyle g=\sin{\left(x \right)} \implies g'=\cos{\left(x \right)}\). Popping up a level gives \(\displaystyle g'=(\sin{\left(x \right)})(18 x - 5)+(9 x^{2} - 5 x + 9)(\cos{\left(x \right)})\)Popping up again (Back to the original problem) gives \(\displaystyle f'=(- 7 x^{2} + 5 x + 7)(\left(18 x - 5\right) \sin{\left(x \right)} + \left(9 x^{2} - 5 x + 9\right) \cos{\left(x \right)})+(\left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)})(5 - 14 x)=\left(5 - 14 x\right) \left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)} + \left(18 x - 5\right) \left(- 7 x^{2} + 5 x + 7\right) \sin{\left(x \right)} + \left(- 7 x^{2} + 5 x + 7\right) \left(9 x^{2} - 5 x + 9\right) \cos{\left(x \right)}\)
\begin{question}Find the derivative of $y = (- 7 x^{2} + 5 x + 7)(9 x^{2} - 5 x + 9)(\sin{\left(x \right)})$.
\soln{9cm}{Identifying $f=- 7 x^{2} + 5 x + 7$ and $g=\left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)}$ and using the product rule with $f=- 7 x^{2} + 5 x + 7 \implies f'=5 - 14 x$. This leaves g as $g = \left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)}$ which also requires the product rule. Pushing down in the new product rule $f=9 x^{2} - 5 x + 9 \implies f'=18 x - 5$ and $g=\sin{\left(x \right)} \implies g'=\cos{\left(x \right)}$. Popping up a level gives $g'=(\sin{\left(x \right)})(18 x - 5)+(9 x^{2} - 5 x + 9)(\cos{\left(x \right)})$Popping up again (Back to the original problem) gives $f'=(- 7 x^{2} + 5 x + 7)(\left(18 x - 5\right) \sin{\left(x \right)} + \left(9 x^{2} - 5 x + 9\right) \cos{\left(x \right)})+(\left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)})(5 - 14 x)=\left(5 - 14 x\right) \left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)} + \left(18 x - 5\right) \left(- 7 x^{2} + 5 x + 7\right) \sin{\left(x \right)} + \left(- 7 x^{2} + 5 x + 7\right) \left(9 x^{2} - 5 x + 9\right) \cos{\left(x \right)}$}
\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>Find the derivative of <img class="equation_image" title=" \displaystyle y = (- 7 x^{2} + 5 x + 7)(9 x^{2} - 5 x + 9)(\sin{\left(x \right)}) " src="/equation_images/%20%5Cdisplaystyle%20y%20%3D%20%28-%207%20x%5E%7B2%7D%20%2B%205%20x%20%2B%207%29%289%20x%5E%7B2%7D%20-%205%20x%20%2B%209%29%28%5Csin%7B%5Cleft%28x%20%5Cright%29%7D%29%20" alt="LaTeX: \displaystyle y = (- 7 x^{2} + 5 x + 7)(9 x^{2} - 5 x + 9)(\sin{\left(x \right)}) " data-equation-content=" \displaystyle y = (- 7 x^{2} + 5 x + 7)(9 x^{2} - 5 x + 9)(\sin{\left(x \right)}) " /> .</p> </p><p> <p>Identifying <img class="equation_image" title=" \displaystyle f=- 7 x^{2} + 5 x + 7 " src="/equation_images/%20%5Cdisplaystyle%20f%3D-%207%20x%5E%7B2%7D%20%2B%205%20x%20%2B%207%20" alt="LaTeX: \displaystyle f=- 7 x^{2} + 5 x + 7 " data-equation-content=" \displaystyle f=- 7 x^{2} + 5 x + 7 " /> and <img class="equation_image" title=" \displaystyle g=\left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)} " src="/equation_images/%20%5Cdisplaystyle%20g%3D%5Cleft%289%20x%5E%7B2%7D%20-%205%20x%20%2B%209%5Cright%29%20%5Csin%7B%5Cleft%28x%20%5Cright%29%7D%20" alt="LaTeX: \displaystyle g=\left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)} " data-equation-content=" \displaystyle g=\left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)} " /> and using the product rule with <img class="equation_image" title=" \displaystyle f=- 7 x^{2} + 5 x + 7 \implies f'=5 - 14 x " src="/equation_images/%20%5Cdisplaystyle%20f%3D-%207%20x%5E%7B2%7D%20%2B%205%20x%20%2B%207%20%5Cimplies%20f%27%3D5%20-%2014%20x%20" alt="LaTeX: \displaystyle f=- 7 x^{2} + 5 x + 7 \implies f'=5 - 14 x " data-equation-content=" \displaystyle f=- 7 x^{2} + 5 x + 7 \implies f'=5 - 14 x " /> . This leaves g as <img class="equation_image" title=" \displaystyle g = \left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)} " src="/equation_images/%20%5Cdisplaystyle%20g%20%3D%20%5Cleft%289%20x%5E%7B2%7D%20-%205%20x%20%2B%209%5Cright%29%20%5Csin%7B%5Cleft%28x%20%5Cright%29%7D%20" alt="LaTeX: \displaystyle g = \left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)} " data-equation-content=" \displaystyle g = \left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)} " /> which also requires the product rule. Pushing down in the new product rule <img class="equation_image" title=" \displaystyle f=9 x^{2} - 5 x + 9 \implies f'=18 x - 5 " src="/equation_images/%20%5Cdisplaystyle%20f%3D9%20x%5E%7B2%7D%20-%205%20x%20%2B%209%20%5Cimplies%20f%27%3D18%20x%20-%205%20" alt="LaTeX: \displaystyle f=9 x^{2} - 5 x + 9 \implies f'=18 x - 5 " data-equation-content=" \displaystyle f=9 x^{2} - 5 x + 9 \implies f'=18 x - 5 " /> and <img class="equation_image" title=" \displaystyle g=\sin{\left(x \right)} \implies g'=\cos{\left(x \right)} " src="/equation_images/%20%5Cdisplaystyle%20g%3D%5Csin%7B%5Cleft%28x%20%5Cright%29%7D%20%5Cimplies%20g%27%3D%5Ccos%7B%5Cleft%28x%20%5Cright%29%7D%20" alt="LaTeX: \displaystyle g=\sin{\left(x \right)} \implies g'=\cos{\left(x \right)} " data-equation-content=" \displaystyle g=\sin{\left(x \right)} \implies g'=\cos{\left(x \right)} " /> . Popping up a level gives <img class="equation_image" title=" \displaystyle g'=(\sin{\left(x \right)})(18 x - 5)+(9 x^{2} - 5 x + 9)(\cos{\left(x \right)}) " src="/equation_images/%20%5Cdisplaystyle%20g%27%3D%28%5Csin%7B%5Cleft%28x%20%5Cright%29%7D%29%2818%20x%20-%205%29%2B%289%20x%5E%7B2%7D%20-%205%20x%20%2B%209%29%28%5Ccos%7B%5Cleft%28x%20%5Cright%29%7D%29%20" alt="LaTeX: \displaystyle g'=(\sin{\left(x \right)})(18 x - 5)+(9 x^{2} - 5 x + 9)(\cos{\left(x \right)}) " data-equation-content=" \displaystyle g'=(\sin{\left(x \right)})(18 x - 5)+(9 x^{2} - 5 x + 9)(\cos{\left(x \right)}) " /> Popping up again (Back to the original problem) gives <img class="equation_image" title=" \displaystyle f'=(- 7 x^{2} + 5 x + 7)(\left(18 x - 5\right) \sin{\left(x \right)} + \left(9 x^{2} - 5 x + 9\right) \cos{\left(x \right)})+(\left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)})(5 - 14 x)=\left(5 - 14 x\right) \left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)} + \left(18 x - 5\right) \left(- 7 x^{2} + 5 x + 7\right) \sin{\left(x \right)} + \left(- 7 x^{2} + 5 x + 7\right) \left(9 x^{2} - 5 x + 9\right) \cos{\left(x \right)} " src="/equation_images/%20%5Cdisplaystyle%20f%27%3D%28-%207%20x%5E%7B2%7D%20%2B%205%20x%20%2B%207%29%28%5Cleft%2818%20x%20-%205%5Cright%29%20%5Csin%7B%5Cleft%28x%20%5Cright%29%7D%20%2B%20%5Cleft%289%20x%5E%7B2%7D%20-%205%20x%20%2B%209%5Cright%29%20%5Ccos%7B%5Cleft%28x%20%5Cright%29%7D%29%2B%28%5Cleft%289%20x%5E%7B2%7D%20-%205%20x%20%2B%209%5Cright%29%20%5Csin%7B%5Cleft%28x%20%5Cright%29%7D%29%285%20-%2014%20x%29%3D%5Cleft%285%20-%2014%20x%5Cright%29%20%5Cleft%289%20x%5E%7B2%7D%20-%205%20x%20%2B%209%5Cright%29%20%5Csin%7B%5Cleft%28x%20%5Cright%29%7D%20%2B%20%5Cleft%2818%20x%20-%205%5Cright%29%20%5Cleft%28-%207%20x%5E%7B2%7D%20%2B%205%20x%20%2B%207%5Cright%29%20%5Csin%7B%5Cleft%28x%20%5Cright%29%7D%20%2B%20%5Cleft%28-%207%20x%5E%7B2%7D%20%2B%205%20x%20%2B%207%5Cright%29%20%5Cleft%289%20x%5E%7B2%7D%20-%205%20x%20%2B%209%5Cright%29%20%5Ccos%7B%5Cleft%28x%20%5Cright%29%7D%20" alt="LaTeX: \displaystyle f'=(- 7 x^{2} + 5 x + 7)(\left(18 x - 5\right) \sin{\left(x \right)} + \left(9 x^{2} - 5 x + 9\right) \cos{\left(x \right)})+(\left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)})(5 - 14 x)=\left(5 - 14 x\right) \left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)} + \left(18 x - 5\right) \left(- 7 x^{2} + 5 x + 7\right) \sin{\left(x \right)} + \left(- 7 x^{2} + 5 x + 7\right) \left(9 x^{2} - 5 x + 9\right) \cos{\left(x \right)} " data-equation-content=" \displaystyle f'=(- 7 x^{2} + 5 x + 7)(\left(18 x - 5\right) \sin{\left(x \right)} + \left(9 x^{2} - 5 x + 9\right) \cos{\left(x \right)})+(\left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)})(5 - 14 x)=\left(5 - 14 x\right) \left(9 x^{2} - 5 x + 9\right) \sin{\left(x \right)} + \left(18 x - 5\right) \left(- 7 x^{2} + 5 x + 7\right) \sin{\left(x \right)} + \left(- 7 x^{2} + 5 x + 7\right) \left(9 x^{2} - 5 x + 9\right) \cos{\left(x \right)} " /> </p> </p>