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Integrate lesson

• To: mathgroup@smc.vnet.net
• Subject: [mg12021] Integrate lesson
• From: Ersek_Ted%PAX1A@mr.nawcad.navy.mil
• Date: Fri, 17 Apr 1998 03:40:56 -0400

User beware.  If you want to use Integrate, DSolve, Solve, etc. on 
complicated expressions
you should ensure the expressions are simplified.  Consider the
contrived  case of Integrate below.  Integrate makes no progress if the
expression  isn't simplified.  However, (expr) can be simplified to
(Sqrt[2] x) so the  integral is just ( x^2/Sqrt[2] ).

First I selected:
 - Cell
     - Default Output Format Type
           - InputForm
__________________________

In[1]:=
expr=Sqrt[2] x - (Sqrt[2]+Sqrt[3])x^x+Sqrt[5+2Sqrt[6]]x^x;


In[2]:=
Integrate[expr,x]

Out[2]=
Integrate[Sqrt[2] x - (Sqrt[2] + Sqrt[3])*x^x +
   Sqrt[5 + 2*Sqrt[6]]*x^x, x]


In[3]:=
FullSimplify[expr]

Out[3]=
Sqrt[2] x


Ted Ersek