问个prep 上的题

Rocky545

DS: if n and p are integers, is p>0?

(1) n+1 > 0,

(2) np >0.

我选E, both together not sufficient.

答案给的是C.both together is sufficient.

(1) + (2):

n>-1, np >0,

if -1<n<0, then p<0,

if n>0, then p>0.

so both together shall not be sufficient.

求NN解释。多谢！

JJJooe

提示你一下

都是整数

Rocky545

汗一个！

多谢！