已知dfrac (y+z)(x)=dfrac (z+x)(y)=dfrac (x+y)(z) +y+zneq 0,,求分式dfrac (y+z)(x)=dfrac (z+x)(y)=dfrac (x+y)(z) +y+zneq 0,,的值

3.利用行列式的性质证明下列等式:-|||-y+z .+x .x+y x y z|-|||-(1) x+y .y+z +x .=2 z x y ;-|||-.z

sin (x+2y-3z)=x+2y-3z, 则 dfrac (partial z)(partial x)+dfrac (partial z)(partial

(2)已知 =V(x,y,z)=dfrac ({x)^2}({a)^2}+dfrac ({y)^2}({b)^2}+dfrac ({z)^2}({c)^2},

试求 dfrac (partial z)(partial x) 和 dfrac (partial z)(partial y).

求直线dfrac (x-1)(1)=dfrac (y)(1)=dfrac (z-1)(-1)-|||-__ __在平面dfrac (x-1)(1)=dfrac

5.设 sin (x+2y-3z)=x+2y-3z, 证明: dfrac (partial z)(partial x)+dfrac (partial z)(pa

殳 =(u)^2ln v =dfrac (y)(x), =2x-3y,-|||-则 dfrac (partial z)(partial y)= ()-|||-A

3设 +2y+z-2sqrt (xyz)=0, 求 dfrac (partial z)(partial x) 及 dfrac (partial z)(parti

直线dfrac (x-1)(2)=dfrac (y)(-1)=dfrac (z-2)(3)-|||-__与直线dfrac (x-1)(2)=dfrac (y)(

直线dfrac (x-1)(1)=dfrac (y-1)(0)=dfrac (z-1)(-1)-|||-__与直线dfrac (x-1)(1)=dfrac (y