x+y=1000 xy=2000 求x,y的值x为完全平方数，两数为正整数

|x|/x+y/|y|+xy/|xy|= sin(x*x+y)=xy 求y'x sin(xy)=x 求dx/dysec(xy)-y ]/x 还是 x/[sec(xy)-y] 1/x-1/y=x,求5y+xy-5y/y-xy-x=? xy-(x+y)=1000 f(x,y)=xy+e^x x arctanx/y ,求f(x+y,x-y) x^2+xy+x=36,y^2+xy+y=20,求x+y. f(xy,x+y)=(x+y)²-xy,求af(x,y)/ax=? 若x^2+xy+y=14,y^2+xy+x=28,求x+y 设x+y=0 ,xy=11,求x*x-xy+y*y 如果x^2+xy+y-14,y^@+xy+x=28,求x+y的值. f(xy,x-y)=x^2-xy+y^2.求f(x,y) xy'=x-y求方程通解 y'+xy=x^3求微分 求xy'+y=x 的通解 sin(xy)=x+y,求dy y'=-2xy;求f(x). x+y=100 求xy