1, DS: M+Z>0

A. M-3z>0

b, 4z-m>0

Answer C.

I think it is E

2, 4 couples, chosee 3 entering the committe, no two people from the same family can serve in the committe.

How many combinations?

Ans: 36

3, A seuqence of numbers, what is x(1)

(1) x(i)=X(i-1)/2

(2)X(5)=X(4)/X(4)+1

Asnwer is C

I think it should be E

because there are two values of X4 can be derived from the two above equation

1 由第一项得M>3Z 第二项得4Z>M 一、二项合并，得4Z>3Z 由此得Z>0 所以Z>0 且M>0

2  我的答案是32 4对里选3对，在这3对里各选一个人，4*2*2*2=32

3  如果题目没有说明这个数列的各项是由不相等的数组成的话，应该是E X(4)有两解，由其中一个解得到的数列是各项全都等于0的，由于碰到过类似的数列题目里有说明各项不相等，所以我怀疑这道题给出的时候漏掉叙述了

请NN指教

the first one should be C.

The second one should be 32, c(1,4) * 2^3.

the third one, x4 could be 0 and 1. Looks like should be E.