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Let "a" and "b" be the roots. Then, according to the condition
  a   - b   = 2      (1)
  a^2 - b^2 = 5      (2)
We can present equation (2) in the form 
    (a+b)*(a-b) = 5.
Replace (a-b) here by 2, based on equation (1), Then you get
    2*(a+b) = 5,
which implies 
    a + b = 5/2 = 2.5.
Hence, instead of (1) and (2), we have this, more simple system of equations
    a - b = 2,      (3)
    a + b = 2.5.    (4)
Add these equations. You will get  2a = 4.5,  which implies  a = 4.5/2 = 2.25.
So, one root is  a= 2.25.  Hence, the other root is 2 unit less  b= 2.25 - 2 = 0.25.
Thus the roots are  a= 2.25, b = 0.25.
Then the quadratic equation under the question is
    (x- 2.25)*(x-0.25) = 0.
You can transform it to any other equivalent form.
Solved.