挑战习题
1/5单选题
难度:

1.

若mn>0,则 的值为( )


A

1

B

-1

C

1或-1

D

1或-3

提示1:
PHA+55SxbW7vvJ4w77yM5Y+v55+lbe+8jG7lkIzlj7fvvIzmiYDku6XliIZt77yMbuWQjOS4uuato+WSjOWQjOS4uui0n+S4pOenjeaDheWGteWIhuWIq+iuqOiuujwvcD4=
提示2:
PHA+be+8jG7lkIzkuLrmraPml7bvvIzljp/lvI89MSsxLTE9MTwvcD4=
提示3:
PHA+be+8jG7lkIzkuLrotJ/ml7bvvIzljp/lvI89LTEtMS0xPS0zPC9wPg==
正确答案:RA==
PGRpdj48cCBhbGlnbj0ibGVmdCI+6Kej77ya55Sx5LqObW7vvJ4w77yM5Y+v55+lbe+8jG7lkIzlj7c8L3A+PHAgYWxpZ249ImxlZnQiPm3vvIxu5ZCM5Li65q2j5pe277yM5Y6f5byPPTErMS0xPTE8L3A+PHAgYWxpZ249ImxlZnQiPm3vvIxu5ZCM5Li66LSf5pe277yM5Y6f5byPPS0xLTEtMT0tMzwvcD48L2Rpdj4=