设两个根为x1 x2，则(x1-1)(x2-1) < 0。使用韦达定理：(x1-1)(x2-1) = x1x2 - (x1 + x2) + 1 = m^2 - (-m+3) + 1 = m^2 + m -2 = (m+2)(m-1) < 0所以 -2 < m < 1
