Evaluate Integral INT sqrt(x^2+6x) dx | Get Help Now

[Mr. Goosemahn]

Homework Statement

Evaluate the integral INT sqrt(x^2+6x) dx

The Attempt at a Solution

I honestly have no clue how to even start. I know it involves trigonometric substitution, but I just can't solve it.

Please Help?

 

[Mark44]

Complete the square.
x^2 + 6x + 9 - 9 = (x + 3)^2 - 3^2.

Now you're set to do a trig substitution. I always draw a triangle, since I don't want to clutter up my brain with what formula goes with what substitution. In that case, the hypotenuse should be x + 3, and either the opposite or adjacent side should be 3.