[求助]GWD-2-35

fhhrewr

先谢谢了

Q35:

p is an integer; n is an integer; and p/n is an integer. Is p/n odd?

(1) p is divisible by 4.

(2) n is divisible by 4.

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

[此贴子已经被作者于2005-1-19 17:34:13编辑过]

sammen

没有思路，我选E

mikejia

1). suppose p=4K, 4K/n=integer if the result is odd, premise is n odd, condition 1 is not enough;

2) Suppose n=4m, if k/4m=odd => k must odd. condition 2 is not enough too

both 1) and 2) together p is even, n is even => p/n=4k/4m=k/m, k and m can be odd or even. so both are not enough.

my choice is E too.

please kindly give some advices.

robert

这道题选E

向这种is的题当无法确定时，只需列出反例即可。

比如由1我们假设p=8 n=2 则8/2=4 而 p=12 n=4 则12/4=3

同理由2也无法确定是否为odd

1+2，我们假设p=4,n=4 则p/n=1 而p=8,n=4则p/n=2

所以E

fhhrewr

谢谢，这种题型比较怪。那么比较通用的解题方法就是举反例啦？

mikejia

我的不通用吗？

不过反例更快更准确。

robert

反例是一种方法，

反证法就是一种通用的方法

sammen

呵呵，俺也是找的反例，这样可能快点。

sammen

真是真理,只要对,管她什么方法不方法的.