The coefficient of x is 1.
Multiply it by .   
Square what you get.        
Add that to both sides of the equation.



The left side now factors as  which we write
simply as , and combine the terms on the right.



Since ,



We take square roots of both sides, remembering the ± on the right:



Now we get two answers, one using the + sign and one using the - sign:

,  

, 

Edwin