Integration by substitution: how to ?

10102014, 10:47 AM
Post: #1




Integration by substitution: how to ?
A very simple example can be the following: INT(1/(x+SQRT(x)))*dx.
Changing variable u=SQRT(x) > u^2=x (with u>=0) > 1/(u^2+u) and dx=2u*dt. The integral now becomes INT(2u/(u^2+u))*du = INT(2/(u+1))*du = 2*ln u+1+c (that is 2*ln SQRT(x)+1+c). How could I do with the Prime ? TIA, Aries 

10102014, 01:37 PM
Post: #2




RE: Integration by substitution: how to ?
assume(u>0); a:=subst('integrate(1/(x+sqrt(x)),x)',x=u^2);
a; 

10112014, 08:16 AM
Post: #3




RE: Integration by substitution: how to ?
Thanks Mr Parisse, much appreciated ;)


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