已知集合M={x|x=3n,n∈Z},N={x|x=3n+1,n∈Z},P={x|x=3n-1,n∈Z},且a∈M,b∈N,c∈P,设d=a-b+c,则A.d∈M B.d∈N C.d∈P D以上都不对答案是a=3n b=3k+1 c=3m-1 d=3n-3k+3m-2 =3n-3k+3m-3+1= 3(n-k+m-1)+1但我唔明既然设了a=3n,点解唔

已知集合M={x|x=3n,n∈Z},N={x|x=3n+1,n∈Z},P={x|x=3n-1,n∈Z},且a∈M,b∈N,c∈P,设d=a-b+c,则A.d∈M B.d∈N C.d∈P D以上都不对答案是a=3n b=3k+1 c=3m-1 d=3n-3k+3m-2 =3n-3k+3m-3+1= 3(n-k+m-1)+1但我唔明既然设了a=3n,点解唔
已知集合M={x|x=3n,n∈Z},N={x|x=3n+1,n∈Z},P={x|x=3n-1,n∈Z},且a∈M,b∈N,c∈P,设d=a-b+c,则
A.d∈M B.d∈N C.d∈P D以上都不对
答案是a=3n b=3k+1 c=3m-1
d=3n-3k+3m-2 =3n-3k+3m-3+1= 3(n-k+m-1)+1
但我唔明既然设了a=3n,点解唔设b系3n+1,C系3n-1

已知集合M={x|x=3n,n∈Z},N={x|x=3n+1,n∈Z},P={x|x=3n-1,n∈Z},且a∈M,b∈N,c∈P,设d=a-b+c,则A.d∈M B.d∈N C.d∈P D以上都不对答案是a=3n b=3k+1 c=3m-1 d=3n-3k+3m-2 =3n-3k+3m-3+1= 3(n-k+m-1)+1但我唔明既然设了a=3n,点解唔
因为虽然M N P中的n都属于z,但a b c是三个集合中任意的三项,a b c中的n不一定相同.比如：a=3,b=4,c=2可以,但a=3,b=7,c=5也可以.n的取值在不同集合间不受影响,可任意取.

因为在本题中n的取值可以一样也可以不一样，他就像是函数中的x一样，只是代表一个变量而已，你要是都设成n的话，就表示他们三个中的自变量必须都只能去一样的值，故不够全面所以在综合写在一个式子离得话应分开写成不同的字母。那为什么 3(n-k+m-1)+1属于d∈N ？ n-k+m-1可能是负数...

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因为在本题中n的取值可以一样也可以不一样，他就像是函数中的x一样，只是代表一个变量而已，你要是都设成n的话，就表示他们三个中的自变量必须都只能去一样的值，故不够全面所以在综合写在一个式子离得话应分开写成不同的字母。

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China denounced the contempt Pacheco TEDA Football
TEDA
Beijing and Tianjin have already passed a couple of days in spite of the war, but nonetheless down TEDA team still pondering over farm...

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China denounced the contempt Pacheco TEDA Football
TEDA
Beijing and Tianjin have already passed a couple of days in spite of the war, but nonetheless down TEDA team still pondering over farmville, its focus is two vertical middle finger Pacheco event. This afternoon, TEDA assistant coach WANG Jian-ying went along to Beijing to go to a Football Association disciplinary committee held a hearing about the Beijing-Tianjin war, there are signs the truth, Pacheco will face heavy fines Commission records.
Derby's hot scenes of Beijing and Tianjin is self-evident, but coach Pacheco's national security door made him the middle finger with the game a main focus. This afternoon, TEDA team conducted a public training, following training Haan accepted a job interview with reporters, but in addition particularly known the middle finger incident. "I don't start to see the king (Jianying) What guidance did the very first gesture, but Pacheco's move however i saw later, the king guide run out, Cleaning it once a to quit Pacheco, hope they can calm and Some restraint,Air Jordan Shoes Release Dates, but sadly, Pacheco eventually sent off, all I'm able to stand,Basketball Shoes, to steer the king did not see things i do. "WANG Jian-ying has carried out what gestures, that angered Paqie Division? In this regard, based on reporters about the situation, WANG Jian-ying at length to the Disciplinary Committee hearing,Air Jordan Retro Shoes, the Commission describes the wedding the whole process.
Based on the Football Association sources, WANG Jian-ying that Pacheco has by no means carried out his insulting gestures,Air Jordan After Game, if the National Security Martin (microblogging) offside, he was assistant referee created a gesture opponents offside, the results allow one to find out Pacheco eyeful. This inference WANG Jian-ying insulting the Portuguese the meaning with the outcomes from the middle finger to fight back. WANG Jian-ying ran the whereabouts of the fourth official complaint, which said this: "I have seen what he did." The effect,Air Jordan Women, so humiliating Pacheco sent off.

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令e=a-b=3n-1
则d=e+c=3n-2=3n+1
选 B