Precalculus (6th Edition) Blitzer

If we don't isolate the radical term, squaring won't get rid of it. (Getting rid of it leads to a simpler equation) Observe the formula for the square of a sum, $(a+b)^{2}=a^{2}+\fbox{$2ab $}+b^{2}$ After squaring both sides we will have $(2x-1)+\fbox{$2\sqrt{2x-1}\cdot 2$}+4=x^{2}$ and the problem to solve isn't any simpler than the one we started out with.