If r, s, and t are nonzero integers, is r5s3t4 negative?

(1) rt is negative.

(2) s is negative.

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

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

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

EACH statement ALONE is sufficient.

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

##### 考题讲解

~$t^4$~一定为正，因此，要判断~$r^5s^3t^4$~的正负只需要判断~$r^5$~和~$s^3$~的正负即可。

（1）  如果满足条件1，例如r=-1，t=1，s=-1，此时~$r^5s^3t^4$~=1为正。如果r=1，t=-1，s=-1，也满足条件，此时~$r^5s^3t^4$~=-1为负，所以，根据条件1无法判断的正负。

（2）    s为负，则~$s^3$~为负，如果r为正，则~$r^5$~为正，~$r^5s^3t^4$~为负；如果r为负，则~$r^5$~为负，~$r^5s^3t^4$~为正。因此，根据条件2无法确定~$r^5s^3t^4$~的正负。