1.求下列函数的高阶偏导数:-|||-(1) =(x)^4+(y)^4-4(x)^2(y)^2 ,所有二阶偏导数;-|||-(2) =(e)^x(cos y+xsin y) ,所有二阶偏导数;-|||-(3) =xln (x,y) dfrac ({a)^3z}(d{x)^2dy} dfrac ({a)^3z}(axa{y)^2} =-|||-(4) =xyz(e)^x+y+z,dfrac ({partial )^p+q+r}(partial {x)^2partial (y)^9partial z} =-|||-(5) =f(x(y)^2,(x)^2y) ,所有二阶偏导数;-|||-(6) =f((x)^2+(y)^2+(z)^2) ,所有二阶偏导数;-|||-(7) =f(x+y,xy,dfrac (x)(y)) ,zx,z(xx,zxy)