解x²-3x=2原式=[(x-1)³-(x²-1)]/(x-1)=[(x-1)³-(x-1)(x+1)]/(x-1)=(x-1)²-(x+1)=x²-2x+1-x-1=x²-3x=2
((x-1)³-x²+1)/(x-1)=(x-1)(x²-2x+1-x-1)/(x-1)=x²-3x因为x²-3x-2=0,即x²-3x=2带入得((x-1)³-x²+1)/(x-1)=(x-1)(x²-2x+1-x-1)/(x-1)=x²-3x=2