Homework Statement
the problem is INTEGRAL 6dz/(z^2(sqrt(z^2+9))
z^2+ a^2 , then z=a*tan@ where a here is 3, because 3^2=9 ,
i use @ here to represent theta
substituting this for z;
Int[6/(z^2(sqrt(z^2+9))]dz= Int[(6*3sec^2@d@)/(9tan^2@(sqrt(9tan^2@+9))]=...