Problem Solving

If (a - b)c < 0, which of the following cannot be true?


A . a < b
B . c < 0
C . |c| < 1
D . ac > bc
E . a^2 - b^2 > 0

Except E i found almost all answers correct.

Source : MGMAT QB

i was trying to sub numbers and check. D seems to be OA for me

in each of the case i am checking out options which satisfy each options and also (a - b)c < 0
A)
a=1
b=2
c=2

B)

a=2
b=1
c=-1

C)
a=2
b=1
c=-1/2


D)
which numbers satisfy this cond


E)
a=2
b=1
c=-1

D for me as well. Whats the OA Bhumika? I usually make mistakes in these Q's

(a-b)c < 0

2 options:

(a-b) > 0 && c<0 - I
(a-b) < 0 && c>0 - II

A. From II, a<b
B. From I, c<0
C. |c| < 1. can be proved easily
D. From the original equation, ac - bc < 0, so ac<bc - Bingo
E. To prove (a-b)(a+b) > 0. We know from I that (a-b)>0, so in that case, (a+b)>0

D.

OA D