Hi again. Trying to solve this by parts. Question is evaluate This is what I get and how I got there. However the answer on the sheet is as below. What am I doing wrong?
Last edited by Craka; June 4th 2008 at 07:55 PM.
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Originally Posted by Craka Hi again. Trying to solve this by parts. Question is evaluate This is what I get and how I got there. However the answer on the sheet is as below. What am I doing wrong? I think your first mistake would be I assumed you let and then and unless I am mistaken
Thanks for you reply, but sorry I don't follow. I did let u=x^2 dv= Sinh(x) du= 2x dx and v= Cosh(x) Are you saying should be v= -Cosh(x) ?
Originally Posted by Craka Thanks for you reply, but sorry I don't follow. I did let u=x^2 dv= Sinh(x) du= 2x dx and v= Cosh(x) Are you saying should be v= -Cosh(x) ? Oh, I am sorry that was a typo, yes you are correct in that v=cosh(x) But isnt the formula for parts So dont you have which is equal to ?
Sorry I made a type in posting my working I have now corrected it, but question still remains on what I have done wrong.
Originally Posted by Craka Sorry I made a type in posting my working I have now corrected it, but question still remains on what I have done wrong. Originally Posted by Craka Hi again. Trying to solve this by parts. Question is evaluate This is what I get and how I got there. However the answer on the sheet is as below. What am I doing wrong? I'm gonna take a shot at this..I haven't dealt with hyperbolic trig in a while.. I believe you have it right, up to here: Apply the FTC, we get: Hope this makes sense!
Where/why did the -Cosh(0) come from? Are you applying the FTC thereom of f(b)-f(a) and if so would you not substitute 0 through all of the expression to evaluate?
Originally Posted by Craka Where did come from. If doing that wouldn't you sub zero in for the whol expression? I take it as you are doing f(b)-f(a) ?? Yes, you would substitute into the whole thing, but note that . Thus, all those terms drop out except for the last one. Yes, I was doing f(b)-f(a).
Sorry that is exactly what you are doing. Just realised of my stupidity.
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