Re: Indefinate integrals, erroneus Natural log?

*To*: mathgroup at smc.vnet.net*Subject*: [mg77901] Re: Indefinate integrals, erroneus Natural log?*From*: nazdrovje at gmail.com*Date*: Tue, 19 Jun 2007 06:42:47 -0400 (EDT)*References*: <f55oor$j6f$1@smc.vnet.net>

Both answers are OK. You seem to have entered or formatted them wrong. The integral should be entered as \[Integral](x \[ExponentialE]^(2 x)) \[DifferentialD]x the textbook answer should be entered as ((1/2) x \[ExponentialE]^(2 x)) - (1/4) \[ExponentialE]^(2 x) Equating both and using FullSimplify results in equality. you merged the x and E (put a space between them). the exponential-e can be entered as esc+ee+esc. Cheers, Naz On Jun 18, 1:02 pm, "David Rees" <w3bdevilREM... at THISw3bdevil.com> wrote: > Hi, > > In preparation for a major exam tomorrow, I was just checking some of my > answers to past-papers with mathematica, I fed it this input: > > In[117]:= > \!\(\[Integral]\((xE\^\(2 x\))\) \[DifferentialD]x\) > Out[117]= > \!\(xE\^\(2\ x\)\/\(2\ Log[xE]\)\) > > I marked myself wrong and moved on to the next question, but I happened > accross the actual mark-scheme which said I was correct. It gave this > answer: > > ((1/2)xE^(2x))-(1/4)e^(2x) > > My Integral calculus isn't so strong, so I don't know if the additional > natural log should be there, or if the two expressions are identical. > > Thanks