b negative

[sanju09]

Is b negative?

(1) a b^3 is negative.

(2) a^3 b is negative.

[ajith]

Is b negative?

(1) a b^3 is negative.

(2) a^3 b is negative.

1) either a or b negative - insuff
2) aither a or b negatie - insuff

both together also is not sufficient since a -ve b +ve as well as b-ve ,a+ve also satisfies 1&2 - Insuff

E IMO

[thephoenix]

imo E
s1)
a*b^3<0
if a<0--->a*b^3<0----->b>0 ......no
if b<0---->a*b^3<0---->b<0........yes

insuff

s2)
a^3*b<0
ifa<0---->b>0.......no
ifa>0---->b<0.......yes

insuff

combining also same........no conclusion
hence E