x+y+z=60,y+z+e=70,y+x+e=80,z+x+e=90算式如何例！

(x+y-z)(x-y+z)= x+y+z=60,y+z+e=70,y+x+e=80,z+x+e=90算式如何例！ x+y+z=e∧（x+y+z）,求σz/σx及σz/σy, x+y+z=e∧（x+y+z）,求σz/x及σz/y, 微积分...设z=z(x,y)是方程^2+y^2+z^2=y*e^z确定的隐函数,求dz.2x/(y*e^z-2z) dx + 2y/(y*e^z-2z) dy X+Y+Z=? x/y=(x+z)/(y+z)y/z=(x+y)/(x+z) 设z=f(x^2-y^2,e^（xy)),求偏导z/x,偏导z/y 已知 x/(y+z)+y/(z+x)+z/(x+y)=1求 (x*x)/(y+z)+(y*y)/(x+z)+(z*z)/(x+y)=? (y+z)/x=(z+x)/y=(x+y)/z求x+y-z/x+y+z的值 x+y+z=15 x+5y+10z=70 x,y,z,各是几? x+y+z=15 x+5y+10z=70 x,y,z,各是几? X+Y-Z=15 X+5Y+10Z=70 求：X、Y、Z 设函数z=z(x,y),由方程z=e^(2x-3z)+2y确定,求∂z/∂x,∂z/∂y 求全微分z=e^[sin(x+y)]*y^x X+Y+Z=15 X+5Y+10Z=70,Y.Z的值 x=y; y=z; z=x/y 设z=f(x,y)由方程z+x+y=e^(z+x+y)所确定,求Dz