2/x+3/y=1,x>0,y>0.问xy最小值是多少?

2/x+3/y=1,x>0,y>0.问xy最小值是多少? 问一条数学题：已知实数x、y满足√(2x-3y-1) + |x-2y+2|=0,求2x- 4/5y的值 设随机变量(X,Y)的概率密度为f(x,y)=1/2(x+y)e∧-(x+y),x>0,y>0.0其他.问X和Y是否相互独立,求Z=X+Y的概 已知x-y=3,x+y=8,问x^2 -y^2=? x+y=3,xy=1,问：y分之x+x分之y= (x+y)(1-x-y)+12=0 问x+y等于多少? 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 {4x-3y-10=0 3x-2y=0,{3x-4(x-y)=2 2x-3y=1,{2(x+y)-(x-y)=3 (x+y)-2(x-y)=1 {x+y=1 ,xy=-6{x(2x-3)=0,y=x²-1{(3x+4y-3)(3x+4y+3)=0,3x+2y=5{(x-y+2)(x+y)=0,x²+y²=8{(x+y)((x+y-1)=0,(x-y)(x-y-1)=0 求问:X>0,Y>0,且X+Y=1,求3/X+4/Y最小值 我问一道数学题 3(x-y)-2(x+y)+2其中x=-1 y=3/4 X-Y=1,X^3-Y^3=2问X^4-Y^4的值 (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 二元一次方程 ：2(x+y)-(x-y)=3 (x+y)-2(x-y)=1 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 2(x+y)-3(x-y)=1 6(x+y)+(x-y)=51 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 变量x,y满足约束条件,x+y>=3,x-y>=-1,2x-y