for x=1:9999 

  y=(sqrt(1988)-sqrt(x))^2;

  if abs(y-round(y))<.00000001

    disp([x,y])

  end

end

Only (x,y) = (497,497) is valid among the below findings, as zero is not positive and the other two purported solutions are due to rounding errors.

                       497                       497

                      1988                         0

                      4473                       497

                      7952                      1988