Question 142436
If your only problem is the negative, just remember that the square root of a number is still just another number.  So anything you can do to a number, you can do to the square root of the number.  By that I mean the following:
If you had the equation 6-2x=2, you could just add 2x to both sides in order to get rid of the negative sign.  So that would become 6=2x+2.
In the problem you gave, 6-√2x=-2 becomes 6=-2+√2x, which you said you know how to solve.  Good luck!