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2x2+xy-3y2+x+4y-1因式分解
已知x.y∈R,求证x2+y2+1≥x+y+xy
已知2x=3y,求xy/(x2+y2)-y2/(x2-y2)的值
已知实数x,y满足(x2)+(y2)-xy+2x-y+1=0,求x,y的值
已知实数x、y满足X2+y2-xy+2x-y+1=0,试求x、y的值
已知X2-2x+y2+6y+10=0,求(x2-2xy)/(xy+y2)的值