inequalities

[nidhis.1408]

Is bd <0
(1) bc < 0
(2) cd >0

Can somebody please give me the answer with explanation. I am a little confused!

[eagleeye]

Is bd <0
(1) bc < 0
(2) cd >0

Can somebody please give me the answer with explanation. I am a little confused!

Hi nidhis.1408:

The easiest way to do this one is to understand what the question is asking and rephrase it.
Is bd<0 translates to: do b and d have opposite signs?

With that in mind let's look at the statements.
(1) bc < 0
Here bc<0 tells us that b and c have opposite signs. It doesn't tell us anything about d. Insufficient.

(2) cd >0
Here cd>0 tells us that c and have the same sign. It doesn't talk about b. Insufficient.

Together,
b and c have opposite signs and c and d have the same sign. Hence, b and d have opposite signs. So bd<0. Sufficient.

Let me know if this helps