6.曲线 ({x)^2+(y)^2) y=4 .

球面^2+(y)^2+(z)^2+4x+6y+2z+10=0的球心坐标为A.^2+(y)^2+(z)^2+4x+6y+2z+10=0B.^2+(y)^2+(z)

6.讨论下列函数的连续性:-|||-(1) (x,y)=dfrac ({x)^2-(y)^2}({x)^2+(y)^2}-|||-(2) (x,y)=dfrac

设:(x)^2+(y)^2=(a)^2 是正向闭曲线，计算曲线积分 :(x)^2+(y)^2=(a)^2设是正向闭曲线，计算曲线积分

设函数y=f(x)由方程(y)^2+(y)^2ln x-4=0所确定,则(y)^2+(y)^2ln x-4=0= ( )(y)^2+(y)^2ln x-4=0(

6.设 (x,y)=dfrac (x-{y)^2+(y)^3}(2x+{y)^2}, 则,lim h(x,y)等于 ()-|||-(A) dfrac (1)(2

( A ) = (x,y,z)|{x)^2+(y)^2+(z)^2=(a)^2,zgeqslant 0} ( B ) = (x,y,z)|{x)^2+(y)^

求旋转曲面=(x)^2+(y)^2在点=(x)^2+(y)^2处的法线方程A.=(x)^2+(y)^2B.=(x)^2+(y)^2C.=(x)^2+(y)^2D

6.用适当的变换计算下列二重积分:-|||-(1) iint sqrt ({x)^2+(y)^2}dxdy = (x,y)|{x)^2+(y)^2leqslan

设f(x,y)= ^4+{y)^2},(x)^2+(y)^2neq 0 0,(x)^2+(y)^2=0 .处是否连续？设,试问在点处是否连续？

设函数 y=y(x) 由方程 ^3+x(y)^2+(x)^2y+6=0 确定,设函数 y=y(x) 由方程 ^3+x(y)^2+(x)^2y+6=0 确定,