Bike Forums > Foo > Calculus math problem
 Register All Albums Elite Membership Forum Rules Calendar Search Today's Posts Mark Forums Read

 Foo Off-Topic chit chat with no general subject.

 10-07-09, 06:31 PM #1 AchiLLe..s Senior Member Thread Starter     Join Date: Oct 2005 Location: Suwanee, Georgia Bikes: Wilier Cento Uno Posts: 312 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) Calculus math problem How do you do the following: Find y' (y prime) y=(tanx)^(1/x) I have no clue how to do this problem
 10-07-09, 06:42 PM #2 riff Senior Member     Join Date: Jul 2008 Location: TO Bikes: Posts: 432 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) I think they want you to find the derivative ( ' ), ie find dy/dx if y=......
10-07-09, 07:07 PM   #3
Hickeydog
Crushing souls

Join Date: Jun 2007
Location: Sagamore Hills, Ohio.
Bikes: Trek 1500
Posts: 1,591
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Take the natural log of both sides (ln). Then you can take the (1/x) down to the front of the ln(tanx). Then take the dirivative of both sides.
__________________
Quote:
 Originally Posted by Wordbiker What's frightening is how coherent Hickey was in posting that.

 10-07-09, 08:23 PM #4 mojopt Senior Member     Join Date: Feb 2009 Location: SW Indiana Bikes: Posts: 166 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) I found y'. It is in the second line of your post...
10-08-09, 05:08 PM   #5
FlatMaster
Genius

Join Date: Jan 2008
Location: Auburn, AL
Bikes: Specilized Sirrus
Posts: 324
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Quote:
 Originally Posted by Hickeydog Take the natural log of both sides (ln). Then you can take the (1/x) down to the front of the ln(tanx). Then take the dirivative of both sides.
When you do this and solve for yprime, you sill may have a y somewhere in your equation. You simply substitute your origional equation for y so you have a function of x only.

 10-08-09, 07:03 PM #6 ehidle T-Shirt Guy     Join Date: Jul 2008 Location: Lansdale, PA Bikes: 2005 Fuji Team Issue, 2007 Fuji SL-1 Posts: 464 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) Use the chain rule, then the quotient rule, then the chain rule again... Just a hint: tanx^(1/x) = exp(1/x ln tanx) and the exponential chain rule d exp(u)/du * du/dx where u = 1/x ln(tanx) __________________ Yellow + Blue Jerseys! Get your Cranky T-Shirt! Men's and Women's designs available Last edited by ehidle; 10-08-09 at 07:14 PM.