(1+x)分之(1-x)-(1-x²)分之(2x²)=1 两边同时乘以(1+x)(1-x)=1-x²得(1-x)²-2x²=1-x²1-2x+x²-2x²=1-x²2x-x²+2x²-x²=1-12x=0x=0