I finally got it using the substitution I mentioned. I think I was screwing up because I didn't change the limits of integration for the new variable. Thanks for the help.
Homework Statement
Evaluate the definite integral from 0 to 18.
∫[x/(9+4x)^1/2]dx
Homework Equations
The Attempt at a Solution
I know to use u-substitution and I set u = (9+4x)^1/2. I can't figure out where I'm messing up because I keep ending up with very large numbers which are...