Detail solution
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Let .
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Apply the power rule: goes to
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Then, apply the chain rule. Multiply by :
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The derivative of cosine is negative sine:
The result of the chain rule is:
The answer is:
The first derivative
[src]
$$- 9 \sin{\left(x \right)} \cos^{8}{\left(x \right)}$$
The second derivative
[src]
7 / 2 2 \
9*cos (x)*\- cos (x) + 8*sin (x)/
$$9 \left(8 \sin^{2}{\left(x \right)} - \cos^{2}{\left(x \right)}\right) \cos^{7}{\left(x \right)}$$
The third derivative
[src]
6 / 2 2 \
9*cos (x)*\- 56*sin (x) + 25*cos (x)/*sin(x)
$$9 \left(- 56 \sin^{2}{\left(x \right)} + 25 \cos^{2}{\left(x \right)}\right) \sin{\left(x \right)} \cos^{6}{\left(x \right)}$$