Can someone please please try and help me with this question thanks.

Find the st values and determine each stationary value (min or max)

y=e^-x(sinx)

When i differentiate I get -e^-x = 0.

What do I do when I get to this stage??

Thanks

## HELP PLEASE stationary values

### Discogirl17

Posted 08 November 2006 - 08:20 PM

Use logs of base e on both sides and u'll end up with x= log of base e to the 0. I think!

### Discogirl17

Posted 09 November 2006 - 11:17 AM

Ah yes he's right. You must now use logs of base e. So you get log to the base e of e to the power of -x, this simply becomes -x since log of e to the e is 1. So you have -x times (cos x- sinx) which becomes -xcosx+xsinx. I'm sure you (using the standard formulas given in past papers and textbooks etc)can rearrange this to form the answer.

P.S I may be wrong, maybe its best to PM Dave, he's the maths wizard! Maths isn't exactly my forte!

P.S I may be wrong, maybe its best to PM Dave, he's the maths wizard! Maths isn't exactly my forte!