| Quadratic equation  (in our case  ) has the following solutons: 
 
  
 For these solutions to exist, the discriminant
  should not be a negative number. 
 First, we need to compute the discriminant
  :  . 
 Discriminant d=0 is zero! That means that there is only one solution:
  . Expression can be factored:
  
 Again, the answer is: 2, 2.
Here's your graph:
 
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