已知df(x,y)=(2y^2+2xy+3x^2)dx+(4xy+x^2)dy,求f(x,y)答案是2xy^2+x^2y+x^3+C

函数f(xy,x+y)=x^2+xy+y^2,则df(x,y)=? 已知df(x,y)=(2y^2+2xy+3x^2)dx+(4xy+x^2)dy,求f(x,y)答案是2xy^2+x^2y+x^3+C 已知x+y=1,xy=-2,则x²y+xy²-2xy 已知x-xy=8,xy-y=-9,求x+y-2xy的值 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 已知：x(x-50y)+xy=50y^2,求：(x-y):y=? 已知X+y=6,xy=7 求x^2y+xy^2=已知X+y=6,xy=7 x^2y+xy^2 已知xy满足约束条件y=2 2X+y 已知X+Y=3XY,求2X+2Y-XY除以X+Y+2XY的值,要算理.已知X+Y=3XY,求2X+2Y-XY除以X+Y+2XY的值,要算理. 已知x-2y=0,求(x/y-y/x)乘xy/x^2-2xy+y^2 已知x+y=-1,xy=-2,求代数式-5（x+y)+(x-y)+x(xy+y)的值 已知,x²+xy=14,y²+xy=2(x>y>0)求x+y.x-y 已知,x²+xy=14,y²+xy=2(x>y>0)求x+y.x-y 已知,x²+xy=14,y²+xy=2(x>y>0)求x+y.x-y 已知xy^2=-2,求-xy（x^2y^5-xy^3-y)的值. 已知xy^2=-2 求-xy(x^2y^5-xy^3-y) 已知xy^2=-2xy(x^2y^5-xy^3-y) 已知x-y=3xy,则2x+3xy-2y除以x-2xy-y=?