{x-2y+3z可得的x:y:z
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1.x+y+z2.-x-3y-1
设x=2K.Y=3k.Z=4kx-y+z分之x+y-z=(2k-3k+4k)分之(2k+3k-4k)=3k分之k=3分之1
(3)式*3+(1)式得3X+Y+3Z=14,(2)式+(3)+(1)得X=3.原方程组的解为X=3,Y=2,Z=1
设x/3=y/4=z/5=k,则x=3ky=4kz=5k带入x+y+z/3x-2y+z,最后约去k就可以了
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
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
因为:X+Y+Z=0得:Z+Y=-X------(1)X+Y=-Z------------(2)Z+Y=-X------------(3)X^3+X^2Z-XYZ+Y^2Z+Y^3=X^3+XZ(X+
因为x:y:z=2:3:4所以设x=2k,y=3kz=4k因为x-y+z=36所以:2k-3k+4k=363k=36k=12所以x+y+z=2k+3k+4k=9k=9×12=108
因为2x=3y=4z可得,x=2z,y=4/3z代入2x-y+z=11/3zx+y+z=13/3z2x-y+z分之x+y+z的值等于13/11
设:x/4=y/5=z/6=k则有:x=4k,y=5k,z=6k(x+y+z)/(3x-2y+z)=(4k+5k+6k)/(12k-10k+6k)=15k/8k=15/8
由柯西不等式(a^2+b^2+c^2)(x^2+y^2+z^2)>=(ax+by+cz)^2,得((1/√2)^2+(1/√3)^2+1)(2x^2+3y^2+z^2)>=(x+y+z)^22x^2+
x-2y+3z=0(1)2x-3y+4z=0(2)(2)x3-(1)x4得:2x-17y=0,2x=17y,x:y=17:2(2)-(1)x2得:-7y-2z=0,7y=-2z,y:z=-2:7=2:
x:y:z=2:3:4令x=2k,y=3k,z=4k(x+y+z)/(x-2y+3z)=(2k+3k+4k)/(2k-2*3k+3*4k)=9k/(8k)=9/8
水晶小cherry:2x+y=7①2y+z=8②2z+x=9③①+②+③,得3x+3y+3z=243(x+y+z)=24即x+y+z=24÷3=8∴x+y+z=8
z=3y/2把:z=3y/2代入x+y+z=3y得:x+y+3y/2=3y整理后得:x=y/2所以:x/(x+y+z)=(y/2)/(y/2+y+3y/2)=1/6不好意思上次算的时候没注意少了y除2
(x+2y-3z)^2+(x-2y+3z)(x+2y-3z)=(x+2y-3z)[(x+2y-3z)+(x-2y+3z)]=(x+2y-3z)(2x)=2x(x+2y-3z)
设x=2t,则y=3t,z=4t3x+2y-z/x+y+z=6t+6t-4t/2t+3t+4t=8t/9t=8/9再问:x:y:z=2:3:4这个可以用两内项之级等于两外项之级吗????再答:可以的。
x+2y+3z=20.(1)x+3y+5z=31.(2)(1)*2-(2)得x+y+z=9
(1)2y-3z=-113Z-2y=11(2)x+z=162x+z=23(3)3x+y=29x+y=15再问:(1)2y-3z=-113Z-2y=11这个连在一起了再答:11。3Z分开