DS 2

[magical cook]

If a and b are positive, is (a^-1 + b^-1)^-1 less than (a^-1b^-1)^-1?
(1) a = 2b
(2) a + b > 1




Hi, [spoiler]I am getting cnfused since a b could be non-integer... can anyone help? [/spoiler]

[Suyog]

The first term - (a^-1 + b^-1)^-1

for any positive value of a and b the first term will always be positive.
coz a^-1 & b^-1 will always be negative so as their addition and then ^-1 of that number will always result in the positive value.

The second term - (a^-1b^-1)^-1
for any positive value of a and b the first term will always be negative.
coz a^-1 & b^-1 will always be negative and their multiplication will always be positive, now ^-1 of the positive number will be again a negative.

So Ans shud be D.
let me know.

[magical cook]

Sorry, it's wrong.. can anyone help us??

[ri2007]

The ans should be C

The lowest values for which a = 2b and a + b > 0 are

b = 0.4 and a = 0.8.

if u put these values or any values greter than then in all cases u will find ab/a+b is less than ab

pls confirm

[magical cook]

Sorry, it's wrong too.. hmm

[lawalx]

the answer dhould be A. pls confirm

[maverick2007]

The ans is A


When we simplify the inequality it comes out to be

Is ab/(a+b)<a/b?

now statement 1 is sufficient to answer this question...

OA please

[syv11]

Hey, I get to ab/(a+b)<ab when simplifying it. Then 1<a+b

Therefore A not sufficient.
B is.

[samirpandeyit62]

Agree with syv11 it should be B

[gabriel]

B for me too ..

[sankruth]

B for me...

Can Magical cook reveal the answer...cos the suspense is killing me!!

[magical cook]

Oops soory for the late reply..... Yes B is the answer. thank you!