高数问题：x^2+y^2+z^2-4x=0,z=f(x,y),求(∂²z)/(∂x&#

已知x²+y²+z²-2x+4y-6z+14=0,求x+y-z/x+y+z的值 分解因式:f(x,y,z)=x^2(y-z)+y^2(z-x)+z^2(x-y) 已知x、y、z满足方程组：x+y-z=6；y+z-x=2；z+x-y=0 求x、y、z的值 x=y/z=z/3,x+y+z ＝12,求2x+3y+4z是多少, 1.已知x,y,z满足2│x-y│+(根号2y-z)+z平方-z+(1/4)=0,求x,y,z值. 已知函数z=f(x^2-y^2,xy),求∂z/∂x,∂z/∂y请各位高 如果|x+y+z-6|+|2x+3y-z-12|+|2x-y-z|=0求x,y, x^2+y^2+z^2+4x+4y+4z+1=0,求x+y+z x^2+y^2+z^2+4x+4y+4z+1=0求x+y+z x^2+y^2+z^2+4x+4y+4z+1=0 求x+y+z x*x+y*y+2z*z-2x+4y+4z+7=0,求xyz的值 若x/2=y/3=z/4不等于0,求x+y+z/x+y-z的值