z=x^2 y^2,z=0和x^2 y^2=2x围成,则此立体体积为
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(y-z)^2+(z-x)^2+(x-y)^2=(x+y-2z)^2+(y+z-2x)^2+(z+x-2y)^2[(y-z)^2-(y+z-2x)^2]+[(z-x)^2-(x+z-2y)^2]+[(
1/x=p1/y=q1/z=rpq+qr+pr=1(y+x)/z+(y+z)/x+(z+x)/y≥2(1/x+1/y+1/z)^2为(pq+qr+pr)[r/p+r/q+q/r+q/p+p/r+p/q
x+y-z=6y+z-x=2z+x-y=0三式相加得x+y+z=8-得2z=2z=1-得2x=6x=3-得2y=8y=4x=3y=4z=1
有这样的公式:a^3+b^3+c^2-3abc=(a+b+c)(a^2+b^2+c^2-ab-bc-ca)左边减右边,证明:(x+y-2z)^3+(y+z-2x)^3+(z+x-2y)^3-3(x+y
2x-3y-4z=01式x+y+z=02式1式+2式×4得到:2x-3y-4z+4x+4y+4z=06x+y=06x=-yx:y=(-1):61式-2式×2得到:2x-3y-4z-2x-2y-2z=0
亲,题目看似很麻烦,仔细想还是有思路的.解:由4x-3y-6z=0,(1式)x+2y-7z=0(2式)(2式)*4得:4x+8y-28z=0(3式)(3式)-(1式)得:4x+8y-28z-(4x-3
x+y+z-6=02x+3y-z-12=02x-y-z=0组成方程组再解x=2y=3z=1
两端对x求偏导得:-ye^(-xy)-2(z/x)+(z/x)e^z=0,所以,z/x=ye^(-xy)/(e^z-2)两端对y求偏导得:-xe^(-xy)-2(z/y)+(z/y)e^z=0,所以,
设a=x-y,b=y-z,-a-b=z-x(y-z)平方+(x-y)平方+(z-x)平方=(y+z-2x)平方+(z+x-2y)平方+(x+y-2z)平方b^2+a^2+(-a-b)^2=(-a-b-
1.z²-z+1/4=(z-1/2)².绝对值、根号、平方数都是非负的,而相加为0.所以都为0.即x=y,2y=z,z=1/2.所以x=y=1/4,z=1/2.2.2002x200
将(x+y+z)²展开有(x+y+z)²=x²+y²+z²+2xy+2xz+2yz=x²+y²+z²所以2xy+2xz+
0和-2再答:0和-2再问:说清是X等于几和z等干几
2x+5y+3z=0,3x+5y-8z=0,两式相减:x-11z=0,所以,x:z=11(1)式乘以3:6x+15y+9z=0(2)式乘以2:6x+10y-16z=0两式相减:5y+25z=0,y:z
=x²(y-z)+y²(z-x)+z²(x-z+z-y)=(y-z)(x²-z²)+(z-x)(y²-z²)=(y-z)(x-z)
X+Y-Z=6.aY+Z-X=2.bZ+X-Y=0.ca,b,c三式相加X+Y+Z=8.dd式-a式2Z=2Z=1d式-b式2X=6X=3d式-C式2Y=8Y=4
括号是什么意思?只有一半
设x/2=y/3=z/5=ax=2ay=3az=5a是不是求的是:(x+3y-z)/(x-3y+z)?若是,如下:(x+3y-z)/(x-3y+z)=(2a+9a-5a)/(2a-9a+5a)=-3
根据公式(a+b+c)^2=a^2+b^2+c^2+2ab+2bc+2ac公式展开:得到(x^2+y^2+z^2=2xy-2yz-2xz)-(x^2+y^2+z^2-2xy-2yz+2xz)合并同类项