求助!!!求助!!!紧急求助三元一次方程计算题

x-2y=-9 y-z=3 2z+x=47
(2)3x-y+z=4 2x+3y-z=12 x+y+z=6
(3)y=2x-7 5x+3y+2z=2 3x-4z=4
(4)4x+9y=12 3y-2z=1 7x+5z=19/4
(5)4x-9z=17 3x+y+15z=18 x+2y+3z=2
(6)2x+4y+3z=9 3x-2y+5z=11 5x-6y+7z=13
(7)x/y=3/2 y/z=5/4 x+y+z=66
(8)3x-y+z=3 2x+y-3z=11 x+y+z=12
(9)5x-4y+4z=13 2x+7y-3z=19 33ab-4ab+8ab-7ab+ab=______．

4．7x-(5x-5y)-y=______．

5．23a3bc2-15ab2c+8abc-24a3bc2-8abc=______．

6．-7x2+6x+13x2-4x-5x2=______．

7．2y+(-2y+5)-(3y+2)＝______．

11．(2x2-3xy+4y2)+(x2+2xy-3y2)=______．

12．2a-(3a-2b+2)+(3a-4b-1)=______．

13．-6x2-7x2+15x2-2x2＝______．

14．2x-(x+3y)-(-x-y)-(x-y)＝______．

16．2x+2y-[3x-2(x-y)]=______．

17．5-(1-x)-1-(x-1)=______．

18．( )+(4xy+7x2-y2)=10x2-xy．

19．(4xy2-2x2y)-( )=x3-2x2y+4xy2+y3．

21．已知A=x3-2x2+x-4，B=2x3-5x+3，计算A+B=______．

22．已知A=x3-2x2+x-4，B=2x3-5x+3，计算A-B=______．

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