{2x+3y=6 3x-2y=-2 {3(x-1)=y+5 5(y-1)=3(x+5) {3/2u+4/3u=2/1 5

随机变量X~N(0,1),Y~U(0,1),Z~(5,0.5)且X、Y、Z相互独立,求随机变量U=(2X+3Y)(4Z- 设全集U=｛（x,y)|x,y属于R｝,集合M={(x,y)|(y-3)除以(x-2)=1},N={(x,y)|y不等于 先化简再求值(x-y)(x+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y 帮忙证明个高数题u=x^2*y^2/(x+y),求证 x*u(x)+y*u(y)=3u 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 已知函数y=[(x+1)^2]u(x)为方程y'-2y/(x+1)=(x+1)^3的通解,求u(x) 已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-( 设全集U={（x，y）|x，y∈R}，集合M={（x，y）|y−3x−2=1}，N={（x，y）|y≠x+1}，则∁U（ 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1