Alright, then make the substitution . Solve for x, calculate in terms of , then substitute everything in the integral in terms of t. When I do that I get . Integrate, then bring everything back to x.
You may have to experiment abit. Try a substitution here and there, and if it looks like a deadend to you, try another one. With practice, you will learn to see what substitutions to make on the go. Sometimes you may need to use integration by parts rather than substitution.