3y-5z=0 5x-4y=0,2x-y z=6
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3x+4y+5z=0(1)2x+3y-4z=0(2)(1)-(2)x+y+9z=0(3)x+y=-9z(2)-2*(3)y-22z=0y=22z代入(3)解得x=-31zx-y=-53z(x+y+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
将Z当成已知数,将X、y用Z来表示2x+3y-4z=03x+4y+5z=0整理得:2x+3y=4z3x+4y=-5z变成二元二次方程解之得:x=-31zy=22z代人x+y+z/x-y+z=2/13
哇,这个很复杂啊再问:你会吗?
将Z当成已知数,将X、y用Z来表示2x+3y-4z=03x+4y+5z=0整理得:2x+3y=4z3x+4y=-5z变成二元二次方程解之得:x=-31zy=22z代人x+y+z/x-y+z=2/13
2x+3y=4z(A式),3x+4y=-5z(B式)A*3-B*2:y=22zA*4-B*3:x=-31z(x+y+z)/(x-y+z)=(-31z+22z+z)/(-31z-22z+z)=2/13
解法2:2x+5y+4z=0式①3x+y-7z=0式②x+y-z=?式①×3-式②×23(2x+5y+4z)-2(3x+y-7z)=015y+12z-2y+14z=013y+26z=0式③式①-式②×
3x+4y+5z=0(1)2x+3y-4z=0(2)(1)-(2)x+y+9z=0(3)x+y=-9z(2)-2*(3)y-22z=0y=22z代入(3)解得x=-31zx-y=-53z(x+y+z)
x+4y+3z=3x-2y-5z=0则x+4y+3z=0①3x-2y-5z=0,则6x-4y-10z=0②①②两式相加,得7x-7z=0,所以x=z代入①,得z+4y+3z=0,所以y=-z所以x+2
4x-5y+2z=0(1)x+2y=3z(2)(2)×4-(1)得:13y=14zy=14/13z(1)×2+(2)×5得:13x=11zx=11/13z所以:x:y:z=11/13:14/13:1=
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
【解】视z为常数,由已知两方程,可解得x=3zy=2z将其代入待求值式中,得3x*x+2y*y+5z*z/5x*x+y*y-9z*z=[3(3z)^2+2(2z)^2+5z^2]/[5(3z)^2+(
【解】视z为常数,由已知两方程,可解得x=3zy=2z将其代入待求值式中,得3x*x+2y*y+4z*z/5x*x+y*y-9z*z=[3(3z)^2+2(2z)^2+4z^2]/[5(3z)^2+(
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
4x-5y+2z=0①x+4y-3z=0②有②得4x+16y-12z=0③①-③得21y-14z=o即Z=1.5Y④④带入①得4X-5Y+3Y=0既X=0.5Y∴x:y:z=0.5Y:y:1.5Y=1
x+2z=3⑴2x+y=2⑵2y+z=7⑶⑴+⑵+⑶=12则x+y+z=4⑷⑴+⑵-⑷,得2x+z=1⑸解二元一次方程⑴⑸,得x=-1/3,z=5/3把x=-1/3代入⑵,得y=8/3所以x=-1/3
应该是3X=4Y,5Y=6Z吧?X+Y:Y+Z=[(4Y/3)+Y]:(Y+5Y/6)=14;11
2式-1式得:X+Y=-9Z……3式1式x2-2式得X+2Y=13Z……4式4式-3式得:Y=22Z代入3式得:X=-31Z于是有:X+Y+Z/X-Y+Z=-31Z+22Z+Z/-31Z-22Z+Z=
2x+3y-4z=0,3x+4y+5z=0两式把z看作已知,可解得x=-31zy=22z(x+y-z)/(x-y+z)=(-31z+22z-z)/(-31z-22z+z)=5/26