x/(x-1)-1=3/(x-1)(x+2)两边乘(x-1)(x+2)x²+2x-x²-x+2=3x=1经检验，x=1时分母x-1=0是增根，舍去所以方程无解
x/(x-1)-1=3/( x²+x-2)x/(x-1)-1=3/(x+2)(x-1)两边同乘以（x+2)(x-1)x(x+2)-(x+2)(x-1)=3x²+2x-x²-x+2=3x=1(增根）方程无解
