F(x,y,y',y'',y''')=0是线性的微分方程吗

(X,Y) f(x,y)={12y^2,0 f(x,y)=e^-y,0 二元函数f(x,y)=x+y/x-y,求f(y/x,x/y) F(x,y)=0 y=f(x), 如果f(x+y-y)=f(x+y)-f(y)那么可不可以推出f(y-x-y)=f(y)-f(x+y) 概率密度f(x,y)=24y(1-x-y),求P{X0,y>0,x+y F(x,y,y',y'',y''')=0是线性的微分方程吗 微积分方程问题F(x,y,y',y'',y''')=0是线性的微分方程吗 f(x,y)=xy+e^x x arctanx/y ,求f(x+y,x-y) f(x,y)={2-x-y,0 概率密度f(x,y )=2-x-y 0 设随机变量（X,Y)~f(x,y)=1,0 设随机变量(X.Y)～f(x,y)=1,0 f(x,y)=A(x+y),0 数学题f(X)对一切x y都有f(x+y)=f(x)+f(y)f(X)对一切x y都有f(x+y)=f(x)+f(y)且x>0时,f(x) f(xy)=f(x)+f(y),证明f(x/y)=f(x)-f(y) y=f(x) y'=y/(x+y) 求y函数的解析式