The equation is .

                                       (Square each side and eliminate the square roots)

  (Add   to each side) \ \

                             ( divide into factors )

                   (Apply zero product property)

                            (Simplify)  

Check:

To check the solution substitute  in .

                                                     (Evaluate square roots: )

The solution is "True".

Check:

To check the solution substitute  in .

                                                 (Evaluate square roots: )

The solution is "false".

The solution is 4.