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Derivative of cos(x)^(x+7)

  • #1
Help! I haven't the slightest clue on how to do this...

thanks in advance!
 

Answers and Replies

  • #2
24
0
Help! I haven't the slightest clue on how to do this...

thanks in advance!
[tex]y=cos^{x+7}(x)[/tex]

Start by taking the natural logarithmic of both sides.
 
  • #3
even the y?

so i'd have:

ln(y) = (x+7)ln(cos(x))

how do i get rid of the ln on the y?

cause i knew it was a ln problem, just i dont know how to get rid of the ln on the y
 
  • #4
306
1
Don't worry about 'getting rid of the ln' yet. The problem is about taking derivatives, so take one and see what happens.
 
  • #5
33,505
5,191
If you take the derivative of the left side, you should get (1/y)(dy/dx). On the right side, you should have the derivative of ((x + 7)ln(cos x)). Solve the resulting equation for dy/dx.
 

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