Question

f'(x)=9x(sinx+cosx)

Answer 1

Question?

Answer 2

sorry this is question..to find derivative of
f(x)=(11tanx+9)/(secx)

Answer 3

this is the one I need help with

Answer 4

there is supposed to be an easy way to simplify it n solve it but I am not sure

Answer 5

Oh I see haha well:
\[\eqalign{
&f(x)=\frac{11\tan(x)+9}{\sec(x)} \\
&=\cos(x)[11\tan(x)+9] \\
&=11\tan(x)\cos(x)+9\cos(x) \\
&=11\sin(x)+9\cos(x) \\
}\]
\[f'(x)=11(\cos(x))+9(-\sin(x))=11\cos(x)-9\sin(x)\]

Answer 6

Make sense?

Answer 7

webworks says that answer is incorrect

Answer 8

Wolfram alpha says it is correct:
http://www.wolframalpha.com/input/?i=d%2Fdx+%2811tan%28x%29%2B9%29%2F%28sec%28x%29%29