#math - Fri 9 Mar 2007 between 03:15 and 03:29

NY Lost Funds

 excelblue let y = x + Sqrt[x^2 + 2x], find the limit on ln yand then after doing that, get the proper thing by doing e^(limit of ln y) again JabberWalkie probably multiply by x-Sqrt[x^2+2x]and divide.. godling that gives me -2x in the numeratorhang onyeah, -2x/x-Sqrt[x^2+2x] excelblue yay, L'Hospital :) kmh zbrown : actually i kinda told you nonsense go with excelblue's substitution excelblue the place you need to go when you have a math problem :P zbrown ;lol ok excelblue well, you could use the Euler formula definitions of sin and cos, work from there using partial fractions kmh zbrown : because partial fraction of that will yield you the expression you already have excelblue just don't expect to be done within 5 pages(of tiny work, that is) kmh zbrown : if you think about it for a minute you'll see why zbrown ya just did godling excelblue: was the bit about e^... towards me? excelblue yeah godling i see excelblue it's one of the hardest parts about first year calculus IMOunless you make lots of simple arithmetic errors - then it becomes the riemann sum w/o a calculator zbrown excelblue: ok so in the case of the int((x+1)/(x^2+4)^2), one side is x, one side is 2, and one side is (x^2+4) right? godling excelblue: how is e involved in computing the limit of this function? zbrown for trig substitution that is kmh zbrown : not quite zbrown kmh: trying to figure it out, not sure where im going wrong? kmh int((x+1)/(x^2+4)^2)= int((x)/(x^2+4)^2)+ int(1/(x^2+4)^2)first part is handled with u=x^2+4, second part with x=tan(u) zbrown kmh: well ok... so for the sides of the triangle, one side is x, one is 2, and one is x^2+4? kmh excelblue*s suggestion was concerning the 2nd part of the sumzbrown : oh you mean a triangle to visualize the trig substitution ? zbrown kmh: ya kmh okzbrown : i don't think you need that but yes it looks okzbrown : basically it is pythagoras zbrown kmh: ok thankskmh: just helps me visualize w/ the triangle :) action zbrown likes pictures zbrown likes pictures