由已知 log2(x+y+3)=log2(xy) 可得xy=x+y+3≥2√xy+3 得（√xy-3）(√xy+1)≥0

已知(x+1)²+|y-1|=0,求2(xy-5xy²)-(3xy²-xy)得值 由已知x+y=-2,xy=3那么2(x+xy)-[(xy-3y)-x]-(-xy)等于多少? 已知2X-3√xy-2y=0(x>0)求2x²+xy-9y²分之x²+4xy-16y
已知x-y=4xy，则2x+3xy-2yx-2xy-y 先化简,再求值 ⒈2(Xy+Xy)-3(Xy-xy)-4Xy,其中X=1,y=-1 已知x^2-xy=5,xy-y^2=-3求3(x^2-xy)-xy+y^2 已知xy^2=-2,求-xy（x^2y^5-xy^3-y)的值. 已知xy^2=-2 求-xy(x^2y^5-xy^3-y) 已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y= 已知y-x-2xy=0,求3x+xy-3y/y-xy-x的值 已知y-x-2xy=0,求(3x+xy-3y)\(y-xy-x)的值 已知3/(x-y)=1/xy 求(-x-2xy+y)/ (2x+3xy-2y)