Question

5.已知函数f(xr,y)=x2-xy2,+求f(2,-1),+f(-1,2),+f(y,2x),

Answer 1

问：5.已知函数f(xr,y)=x2-xy2,+求f(2,-1),+f(-1,2),+f(y,2x),+f(2+Or,3),+f(2

答：f(x+y,y/x)=x²-y²令u=x+y，v=y/x则x=u/(v+1)、y=vu/(v+1)f(u,v)=u²/(v+1)²-u²v²/(v+1)²=u²(1-v²)/(v+1)²f(x,y)=x²(1-y²)/(y+1)²

问：6.求下列函数的定义域.(1) z=√4-4x2-y2;

问：6.求下列函数的定义域.(1) z=√4-4x2-y2;

答：再给你计算中