posted by mathstudent .
Integrate x/(x^2 + 4) dx via trig substitution and by u=x^2+4 substitution. Show that results are equal.
Via trig substitution of x=2 *tan t, I get:
1/2 * tan^-1 (x/2) + c
Via u = (x^2 + 4) substitution, I get:
1/2 * ln |x^2 + 4| + c
How are these equal?