Since the radical is already isolated on the left,
square both sides.









Get 0 on the left by subtracting  from
both sides:



or



Factor left side:



Use the principle of zero factors:

  

But we have to check each of those,
because squaring both sides, or multiplying
both sides by a variable, may result in
bogus solutiona, called "extraneous"
solutions.

Checking 







That checks, so  is a solution.

Checking 







That does not check, so  is not 
a solution, and is called "extraneous".

The only genuine solution is 

Edwin