Posted by Salman on Monday, December 14, 2009 at 3:19pm.
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=?

Calculus  Reiny, Monday, December 14, 2009 at 4:53pm
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 
Calculus  Salman, Monday, December 14, 2009 at 7:06pm
neither of these videos explain the situation where vaiable x is in the numerator, so i still cant solve it