∵ mx²-(m-1)x+m-5=0有两个实根a、b (m-1)²-4m*(m-5)>0 -3(m-3)²+28>0 (m-3)²<28/3 ∴ 3-√(28/3) ∵-1 -1 -1<(m-5)/m <0 , -1< (1-m)/m <1 -1<1-(5/m) <0 , -1< (1/m ) -1 <1 1<5/m<2 , 0 <1/m < 2 ∴ 2.50.5 ∴ 2.5