若x-2y+10z=5,2x+5y-7z=1,则x+y+z=?

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(y-x)/(x+z-2y)(x+y-2z)+(z-y)(x-y)/(x+y-2z)(y+z-2x)+(x-z)(y-z

∑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)]=? kuai

(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

{2x+3y-4z=-5 x+y+z=6 x-y+3z=10

(1)2x+3y-4z=-5(2)x+y+z=6(两边同时×33x+3y+3z=18(与(1)相减得(5)(3)x-y+3z=10(与(2)相加得(4))(4)2x+4z=16(5)x+7z=23(两

若x/3=y/4=z/5,求x+y+z/3x-2y+z的值.

设x/3=y/4=z/5=m则x=3m,y=4m,z=5m则x+y+z/3x-2y+z=(3m+4m+5m)/(9m-8m+5m)=12/6=2

x+y−2z=52x−y+z=42x+y−3z=10

方程(1)+(2)得:3x-z=9④,方程(2)+(3)得:2x-z=7⑤,④-⑤得:x=2,把它代入⑤得:z=-3,把它代入(1)得:y=-3,∴原方程的解为x=2y=−3z=−3.

化简(y-x)(z-x)/(x-2y+z)(x+y-2z)+(z-y)(x-y)/(x-2z+y)(y+z-2x)+(x

∵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,z正整数 x>y>z证明 x^2x +y^2y+z^2z>x^(y+z)*y^(x+z)*z^(x+y)

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

已知x::y:z=3:4:5,(1)求x+y分之z的值;(2)若x+y+z=6,求x,y,z.

因为x:y:z=3:4:5所以设x=3k,y=4k,z=5k(k≠0)(1)z/(x+y)=5k/(3k+4k)=5k/7k=5/7(2)x+y+z=63k+4k+5k=612k=6k=1/2x=3k

2X+Y+Z=10,X+2Y+Z=-6,X+Y+2Z=8 5X+4Y-3Y=13,2X-3Y+7Z=19,3X-Y=2X

2x+y+z=10(1)x+2y+z=-6(2)x+y+z=8(3)(2)-(3):y=-14(4)(1)-(2):x-y=16(5)把(4)代入(5):x+14=16x=2(6)把(4)和(6)代入

若4x=7y+5z,2x+y=z,则x:y:z的值为

把z=2x+y代入4x=7y+5Z得4x=7y+10x+5yx=-2y,z=-3yx:y:z=-2:1:-3

若4x-3y-6z=0,x+2y-7z=0,求代数式5x*5x+2y*2y-z*z/2x*2x-3y*3y-10z*10

题目设置挺好的不会很变态,没什么难度由4x-3y-6z=0,x+2y-7z=0,可以解得x=3z,y=2z,将它代入代数式5x*5x+2y*2y-z*z/2x*2x-3y*3y-10z*10z=(25

{5X+Y+Z①X+5Y+Z=-2②X+Y+5Z=10③

①+②+③6X+6Y+6Z=14X+Y+Z=7/3④①-④4X=11/3X=11/12③-④4Y=-13/3Y=-13/12③-④4Z=23/3Z=23/12

若x+2y-4z=0 3x+y-z=0 求x:y:z

①x+2y-4z=0②3x+y-z=0①-2②x-6x-4z+2z=05x=2z代入①z=5x/2x+2y-10x=02y=9xy=9x/2x:y:z=1:9/2:5/2=2:9:5

2x+y+3z=383x+2y+4z=564x+y+5z=66

2x+y+3z=38①3x+2y+4z=56②4x+y+5z=66③③-①得:2x+2z=28,即x+z=14④,①×2-②得:x+2z=20⑤,由④和⑤组成方程组:x+z=14x+2z=20,解得:

因式分解:25x y^2 z^2 (x+y-z)-30xyz(z-x-y)^2+5x y z^3 (z-x-y)

25xy^2z^2(x+y-z)-30xyz(z-x-y)^2+5xyz^3(z-x-y)=25xy^2z^2(x+y-z)+30xyz(x+y-z)^2-5xyz^3(x+y-z)=5xyz(x+y

x/2=y/3=z/5 x+3y-z/x-3y+z

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

若2分之x+y=3分之y+z=5分之x+z 且x+y+z=18 求x,y,z的值

设2分之x+y=3分之y+z=5分之x+z=k则x+y=2k,y+z=3k,x+z=5k3式相加得2(x+y+z)=10k=18*2=36,k=3.6,x+y+z=5kz=5k-2k=3k=10.8x