Let a = 2 and b = 1. Noting that (a^2)b - 4 = 0 = a^2 + 2a = b - 1, we have:


                     b  =  b

         (a^2)b - 4 + b =  b

         (a^2)b - 4 + b =  b + b(a^2 + 2a)

         (a^2)b + b - 4 =  b(a^2 + 2a) + 4(b - 1) + b

   (a^2)b + 2ab + b - 4 =  (a^2)b + 4ab + 4b + b  4

           (a^2)b + 2ab =  (a^2)b + 4ab + 4b

              ab(a + 2) =  b(a + 2)^2

                    ab  =  b(a + 2)

                     a  =  a + 2

                     2  =  0

                     1  =  0.