Calculus
posted by Salman .
For the following integral find an appropriate TRIGONOMETRIC SUBSTITUTION of the form x=f(t) to simplify the integral.
INT (x^2)/(sqrt(7x^2+4))dx dx x=?

This is the first of several YouTube clips where Khan shows in nice detail how to work trig substitution.
http://www.youtube.com/watch?v=n4EK92CSuBE&feature=youtube_gdata
This is part of
http://www.khanacademy.org/
which is a wonderful collection of hundreds of YouTube clips showing most of the mathematical procedures up to college level Calculus.
Let me know if this was helpful 
neither of these videos explain the situation where vaiable x is in the numerator, so i still cant solve it