1-4x四次方/2x的三次方+x=(1-2x²)(1+2x²)/x(2x²+1）=(1-2x²)/x=(1-8)/(-2)=7/2(2)x²y-2xy+y/y-x²y,其中x=-2；原式=y(x-1)²/y(1+x)(1-x)=1-x/(1+x)=3/(-1)=-3（3）a²-3ab/a&...