f(x) = 0 হলে `x^2 - 4x + 3 = 0` বা, `x^2 - 3x - x + 3 `= 0 বা, x(x - 3) - (x - 3) = 0 বা, (x - 3) (x - 1) = 0 :. x = 3, 1