8x+10y=1252 x+y=143 问x=?y=?

x+y=17 x+x+y+y+y+y=44问x和y各是多少 3X+8Y=51 X+6Y=21 问X=?Y=? Y-X*0.09=2500 求问Y、X是多少. 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 已知10y=7.5x,请问10y-7x=y+3.14,问x-y=几 (4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai 二元函数f(x,y)=x+y/x-y,求f(y/x,x/y) 协方差计算如何展开?cov(x+y,x-y)=cov(x,x)-cov(x,y)+cov(y,x)-cov(y,y)求问 [x(x-y)-y(x-y)+(x+y)(x-y)]÷2x其中x=2012 y=2013 已知/x/+x+y=10,/y/+x-y=12.求x+y的值 已知2x-y=10,求[(x²+y²)-(x-y)²+2y(x-y)]/4y ) y=cos(x-y)