若x/3=y/4=z/5不等于0,则
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![若x/3=y/4=z/5不等于0,则](/uploads/image/f/6966656-8-6.jpg?t=%E8%8B%A5x%2F3%3Dy%2F4%3Dz%2F5%E4%B8%8D%E7%AD%89%E4%BA%8E0%EF%BC%8C%E5%88%99)
67/78,令3x=4y=5z=60k即可
方程组两边除以z得4x/z-3y/z=3x/z-3y/z=-1解方程组得x/z=4/3y/z=7/9
令(x+y)/3=(y+z)/5+(z+x)/4=k所以x+y=3k(1)y+z=5k(2)z+x=4k(3)相加2(x+y+z)=12kx+y+z=6k(4)用(4)分别减去(1)(2)(3)z=3
30:3:5再问:稍微说一下理由谢谢!
解由5分之x=4分之y=3分之z令5分之x=4分之y=3分之z=k则x=5k,y=4k,z=3kk不等于0则3x-2y分之x+y+z=(3x-2y)分之(x+y+z)=(3*5k-2*4k)分之(5k
4x-5y+2z=0①x+4y-3z=0②由①+②得:5x-(y+z)=05x=y+z由②*4-①得:21y-14z=0y=2z/35x=2z/3+z=5z/3x=z/3x:y=(z/3):(2z/3
x=4yz=5x=20y(x-14y+3z)/(x+y+z)=(4y-14y+20y)/(4y+y+20y)=10y/25y=2/5回答完毕
4x-3y-3z=x-3y+z=04x/z-3y/z-3=0.①x/z-3y/z+1=0.②①-②得:3x/z-4=0x/z=4/3代入②得:4/3+1-3y/z=0y/z=7/9x:y=(4/3)/
4x-3y-3z=0.1)x-3y+z=0.2)相减:3x=4zx/z=4/31)-2)*4:9y=7zy/z=7/9所以:x/z=4/3,y/z=7/9
4x-3y-3z=0(1)x-3y+z=0(2)(1)-(2):3x-4z=0x=4z/3代入(1):16z/3-3y-3z=0y=7z/9所以:x:z=4:3y:z=7:9
31x+19y-23应该是:31x+19y-23z,少了一个z就不好解答了4x-5y+2z=0①x+4y-3z=0②由①+②得:5x-(y+z)=0所以5x=y+z由②*4-①得:21y-14z=0所
4x+5y+2z=0(1)x+4y-3z=0(2)由(2)x=3z-4y(3)(3)代入(1)12z-16y+5y+2z=014z-11y=011y=14zy=14z/11(4)(4)代入(3)x=3
x=3ky=4kz/x=5/3相加为7k+5/3
由第一个方程得:x/y=3/2然后代入第二个方程得:y/z=6/11再得x=3/2yz=11/6y代入所求的式子得x:y:z=9:6:11
x/3=y/5=z/7=kx=3k,y=5k,z=7k2x+3y+4z/5x-3y+z=(6k+15k+28k)/(15k-15k+7k)=7
(x-3y+z)+(3x-3y-4z)=0,则4x=3y,x:y=3:4(x-3y+z)-(3x-3y-4z)=0,则2x=5z,x:z=5:2则x:y:z=20:15:8
(1/2)x=(1/3)y=(1/4)z=kx=2k,y=3k,z=4kx:y:z=2:3:4
(4x/z)-(5y/z)=-2……①(x/z)-(4y/z)=3……②方程②×4得,(4x/z)-(16y/z)=12……③①-③得,11y/z=-14,∴y/z=-14/11代入②得,(x/z)-
令a=x/2=y/3=z/4则x=2a,y=3a,z=4a所以原式=(2a+3a+4a)/(2a+3a-4a)=9a/a=9