I'm having trouble finding the answer to this problem. The square root is supposed to be over all of the x + y + 1.
Note that when we integrate with respect to y, x+1 is considered a constant, let's say A.
The integral becomes
Now to evaluate this integral, you can make a simple substitution: . The limits of integration change as well! and
Thus, we now have
Now plugging back and simplifying, we end up with
I'm sure you can take it from here.
I'm going to assume you're integrating by x and then by y. In this case it doesn't matter if it's the opposite, but sometimes it does.
The key is just remembering that the square root of a number is just an exponent of 1/2.
From here you're going to integrate as with any normal exponent. Add one to it and multiply the front by the inverse. Then just plug in 1 and 0 for x and subtract.
Just repeat for the other variable and you'll be there soon enough.