求助各位大虾几道数学题?

mymengming

以下是引用anclewu在2006-7-24 13:48:00的发言：

2 is in S-> -2 is in S. Since 2 and -2 are both in S, then -4 is in S.

Hope it is clear.

yes, that is right!!

mymengming

以下是引用peterbin413在2006-7-23 23:43:00的发言：

第一题我也选得是B，可答案给的是D，我不太明白此题的解法

D is the right choice

anclewu

以下是引用lovetiky在2006-7-24 13:42:00的发言：

不能解释一些么？

2 is in S-> -2 is in S. Since 2 and -2 are both in S, then -4 is in S.

Hope it is clear.

lovetiky

以下是引用anclewu在2006-7-24 13:37:00的发言：

Answer is D.

2.S is a set of integers such that

(1)if a is in S,then -a is in S,and

(2)if each of a and b is in S,then ab is in S, Is -4 in S?

1. 1 is in S  2.  2 is in S      此题属于没有看懂的

Answer is B

不能解释一些么？

anclewu

以下是引用peterbin413在2006-7-23 17:57:00的发言：

小弟刚刚接触GMAT，数学上还有很多盲点，望各位热心的大侠们鼎力相助阿，受小弟一拜！

1.m为连续偶数，问k>m?

(1)k+2同m-2不为连续偶数（2）k-1同m+3为连续奇数

Answer is D.

2.S is a set of integers such that

(1)if a is in S,then -a is in S,and

(2)if each of a and b is in S,then ab is in S, Is -4 in S?

1. 1 is in S  2.  2 is in S      此题属于没有看懂的

Answer is B

yaoyao99

Please please include the source of your question (e.g. OG-xxx, GWD-xx-yy) in the subject line!

peterbin413

第一题我也选得是B，可答案给的是D，我不太明白此题的解法

tikyluo

1.m为连续偶数，问k>m?

(1)k+2同m-2不为连续偶数（2）k-1同m+3为连续奇数

The correct answer is B.

if k-1=m+5, then k=m+6

if k-1=m+1, then k=m+2.

apparently, the answer is B.

2.S is a set of integers such that

(1)if a is in S,then -a is in S,and

(2)if each of a and b is in S,then ab is in S, Is -4 in S?

1. 1 is in S  2.  2 is in S      此题属于没有看懂的

well, so do i. i can't understand the question.

3.If x,y,z are single-digit integers and 100(x)+1000(y)+10(z)=N,what is the units'digit of the number N?

A0 B1 Cx Dy Ez

apparently,the correct answer is A.

4.All of the following have the same number of distinct prime factors exept

A20 B21 C24 D30 E45

the correct answer is D.

A 20=2*2*5(2 5)

B 21=3*7(3 7)

C 24=2*2*2*3(2 3)

D 30=2*3*5(2 3 5)

E 45=3*3*5(3 5)

 

GOOD LUCK, guy.

peterbin413

小弟刚刚接触GMAT，数学上还有很多盲点，望各位热心的大侠们鼎力相助阿，受小弟一拜！

1.m为连续偶数，问k>m?

(1)k+2同m-2不为连续偶数（2）k-1同m+3为连续奇数

2.S is a set of integers such that

(1)if a is in S,then -a is in S,and

(2)if each of a and b is in S,then ab is in S, Is -4 in S?

1. 1 is in S  2.  2 is in S      此题属于没有看懂的

3.If x,y,z are single-digit integers and 100(x)+1000(y)+10(z)=N,what is the units'digit of the number N?

A0B1CxDyEz

4.All of the following have the same number of distinct prime factors exept

A20B21C24D30E45