一、3X+y=8211X-9Y=22求X和Y的值二、芜湖供电公司分时电价执行时段分为平、谷两个时段,平段为8：00~22：00,14小时,而谷段为22：00~次日8：00,10小时,平段用电价格在原销售电价的基础上每千瓦时上

已知:3x-5y=0,求x/y,x-y/y,x-y/x 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 求函数f（x,y）=x×x×x－y×y×y+3×x×x+3×y×y－9x的极值 已知3x =2y 求x/x+y+y/x-y-y²/x²-y² 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 已知2x-y/x+2y=3,求2(2x-y)/x+2y-9(x+2y)/2x-y+3的值. 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 已知|x|=2,|y|=3,|x+y|=-(x+y)求x-y (x+y)(x+y-10)+25=0,且x-y=3,求x,y (x+y)(x+y-10)+25=0,且x-y=3,求x,y y=3(x-y),x=2(x-y)求x,y的值 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) x(x-3y)=4y(x-3y),求x:y 已知|3x-y|+|x+y|=0,求x-y除以x*y的值. x/3=y/4,求(x*x-xy)/(x*x+y*y)的值 己知x平方+3xy一4y平方=0(y≠0)求代数式(1)y分之x(2)x+y分之x一y 二元函数f(x,y)=x+y/x-y,求f(y/x,x/y) 9x+2y=62.4x+3y=36.求x,y