x+y-2z=5,2x-y+z=4,2x+y-3z=10
来源:学生作业帮助网 编辑:作业帮 时间:2024/04/28 00:16:37
1.x+y+z2.-x-3y-1
(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
∑是循环和例如∑a=a+b+c∑a^2=a^2+b^2+c^2∑(z-y)(x-y)/(x+y-2z)(y+z-2x)=∑(z-y)(x-y)(x+z-2y)/(x+y-2z)(y+z-2x)(x+z
(4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=4x-2y-z-5x[6y-(x+y)]+x-(3y-10z)=4x-2y-z-30xy+5x²+5xy+x-3
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
∵x-2y+z=(x-y)-(y-z),x+y-2z=(y-z)-(z-x),y+z-2x=(z-x)-(x-y).设x-y=a,y-z=b,z-x=c,则原式=-ac/(a-b)(b-c)+(-ba
x+y=z2x-3y+2z=5x+2y-z=3第三个式子乘2得2x+4y-2z=6加上第二个式子4x+y=11第一个式子代入第三个式子得y=3,则x=2代入第一个式子,z=5
正整数?取对数即证:2xlnx+2ylny+2zlnz>(y+z)lnx+(x+z)lny+(x+y)lnzx>y>z,lnx>lny>lnz由排序不等式得xlnx+ylny+zlnz>ylnx+zl
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-
x+y+z=2(1)x-3y+2z=1(2)2x+2y+z=5(3)(1)×2-(2)得:x+5y=3(4)(3)-(1)得:x+y=3(5)(4)-(5)得:y=0代入(5)得:x=3代入(1)得:
3式相加,得x+y+z=2所以,容易得,x=3,y=-1,z=0
z=x+y(1)3x-2y-2z=-5(2)2x+y-z=3(3)由(1)得x+y-z=0(4)(3)-(4)得x=3把x=3代入(2)得9-2y-2z=-5y+z=7(5)把x=3代入(4)得y-z
这个题目没有问题么,我是说最后一个式子确定是z+5y+8z=-2?如果没有问题的话:x+y+z=1;①x+3y+7z=-1;②z+5y+8z=-2③①-②2Y+6Z=-2Y=(-2-6Z)/2=-1-
x+y-z=0①,2x-3y+2z=5②,x+2y-z=3③,①-③=x+y-z-﹙x+2y-z﹚=﹣3,y=3,将y=3代入①②中分别为,x-z=﹣3④,x+z=7⑤,④﹢⑤=2x=4,x=2,将x
=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=0(1)x+2y-z=3(2)2x-3y+2z=5(3)2-1式得y=3将y=3代入2、3得x-z=-3(4)x+z=7(5)4+5式得2x=4解得x=2y=5综合得x=2y=3z=5
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