October 30th, 2008, 04:28 PM  #1 
Newbie Joined: Oct 2008 Posts: 3 Thanks: 0  tangent to x^x
the problem is find tangent line to x^x that passes through origo. i didnt get far: y=x^x lny=x*lnx y=e^(x*lnx) dy/dx = e^(x*lnx)*(x*1/x +lnx) = x^x(lnx +1) (is this derivative correct?) so, dy/dk must equal the slope of the line that passes though origo and so has equation y = (dy/dx)*x and im pretty much stuck here. Any help much appreciated! 
October 30th, 2008, 05:05 PM  #2 
Senior Member Joined: Mar 2007 Posts: 428 Thanks: 0  Re: tangent to x^x
Differentiate in the second line implicitly. y=x^x, so ln(y) = xln(x) <Here. Then separate variables and sub back for y. Too many late nights and I'm too tired to go on. 
November 2nd, 2008, 01:16 PM  #3 
Global Moderator Joined: Oct 2008 From: London, Ontario, Canada  The Forest City Posts: 7,517 Thanks: 910 Math Focus: Elementary mathematics and beyond  Re: tangent to x^x 

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