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(x-y+z)²等于多少

x+z=2y 解: (x-z)²-4(x-y)(y-z)=0 (x-y+y-z)²-4(x-y)(y-z)=0 (x-y)²+(y-z)²+2(x-y)(y-z)-4(x-y)(y-z)=0 (x-y)²+(y-z)²-2(x-y)(y-z)=0 [(x-y)-(y-z)]²=0 (x+z-2y)²=0 x+z-2y=0 x+z=2y

你好 (x+y+z)(-x+y+z)(x-y+z)(x+y-z) =[x+(y+z)] [(y+z)-x] [x-(y-z)] [x+(y-z)] =[(y+z)²-x²][x²-(y-z)²] =(y+z)²x²-(y+z)²(y-z)²-x⁴+x²(y-z)² =x²[(y+z)²+...

(x+y+z)²-(x-y-z)² =[(x+y+z)+(x-y-z)][(x+y+z)-(x-y-z)] =2x×(2y+2z) =4x(y+z)

求偏导数就把别的参数看作常数即可 f(x,y,z)=x²y+y²z+z²x 于是f'x=2xy+z²,f'y=2yz+x² 继求偏导得到 f''xx=2y,f''xy=2x,f''yz=2y,而f'''xxy=2 即f''xx(1,0,0)=0,f''xy(1,0,1)=2 f''yz(1,0,2)=0,f'''xxy=2

(x+y+z)(x+y-z) =(x+y)²-z² = x²+2xy+y²-z²

解: x²+y²+2z²-2xz+2yz=0 (x²-2xz+z²)+(y²+2yz+z²)=0 (x-z)²+(y+z)²=0 平方项恒非负,两非负项之和等于0,两非负项均等于0 x-z=0 y+z=0 解得x=z,y=-z 2x+y-z=2z-z-z=0 2x+y-z的值为0

由于积分区域Ω:x² + y² + z² = R²关于坐标三轴都对称 且被积函数中的x,y,z都是奇函数 若f(x,y,-z)=-f(x,y,z),则说f(x,y,z)关于z是奇函数 在对称区间上的奇函数的积分结果是0 所以用对称性可得∫∫∫ (x+y+z) dV = 0 剩下的∫∫...

解: x²+y²-2xy=(x-y)² y²+z²-2yz=(y-z)² z²+x²-2zx=(z-x)² 上面三式相加得: 2(x²+y²+z²-xy-yz-zx)=(x-y)²+(y-z)²+(z-x)² x²+y²+z²-xy-yz-zx=...

=(2xy)²-(x²+y²-z²)² =(2xy+x²+y²-z²)(2xy-x²-y²+z²) =[(x+y)²-z²][z²-(x-y)²] =(x+y+z)(x+y-z)(z+x-y)(z-x+y)

az/ax=[(x+y)-(x-y)]/(x+y)² =2y/(x+y)² az/ay=[-(x+y)-(x-y)]/(x+y)² =-2x/(x+y)² dz=2y/(x+y)² dx-2x/(x+y)²dy

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