Question

(1) 1/x-1/y=3,分式(2x+3xy-2y)/(x-2xy-y)=_______

Answer 1

1:1/x-1/y=3(y-x)/xy=3y-x=3xyx-y=-3xy所以(2x+3xy-2y)/(x-2xy-y)=[2(x-y)+3xy]/[(x-y)-2xy]=-3xy/-5xy=3/5 2:K²-23:2/34:-11/m+1/n=1/(m+n)(m+n)^2=mnn/m+m/n=(n^2+m^2)/mn=(n^2+m^2+2mn)-2mn/mn=[(m+n)^2-2mn...