请不吝赐教

mariezhu

Is x negative?
1.n^3*(1-x^2)<0
2.x^2-1<0

dreadpower

   我觉得选

   条件1得1-x^2>0或者1-x^2<0，不管是哪种情况都不能知道X是否是负数

   条件2得 -1<X<1同样不行

   条件1和2得N<0，且-1<X<1，还是不知道X是否为负数

   所以选E

mariezhu

我和GG有强烈同感,可是手头的答案竟然是C,颇有些不知所以然啊

lwei1016

偶也选E.

springappleleaf

I select E

lucre

it must  be a typo

my guess is

1.x^3*(1-x^2)<0
2.x^2-1<0

mariezhu

1.n^3*(1-x^2)<0
2.x^2-1<0

Don't understand, what's the difference btwn yours and mine?

tianwan

merie：你的是 1.n^3*(1-x^2)<0， lucre's is 1.x^3*(1-x^2)<0
If what lucre typed is the original one, then choice C makes sense.

mariezhu

哦,不好意思,我太粗心了.

有道理,可能是因为这个原因