Prep math Questions, no one asked before

sunnyfields

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

sunnyfields

thanks to all!!!!!

creditadvices

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.

AlphaBeta

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