quadratic

epand R side   x^2 + 2a x+ a^2

equating to L side   shows    2a = -77     ( the 'x' coefficients)

                                            a = -38.5

 

                                        and a^2 = c        so c = (-38.5)^2 = 1482.25

 

 

      ( x-38.5)^2   = x^2 - 77x + 1482.25