x=1/x,x²=1,x=±1；
[（x²+2x-3）/（x-1)]/[（x+3）/（x²-3x+1）]
=（x+3)(x-1)(x²-3x+1）/[（x-1)(x+3)]
=x²-3x+1
=1±1*3+1=2±3
=5或-1