yashikaaggarwal
Bunuel
BijayKru
I think the answer will be C
(M+N)^2 = M^2 +N^2 +2MN
SO WE HAVE ALL THE VALUE IN I AND II. SO why not C is the answer.
There is a solution given
HERE explaining why the answer is E and not C.
So basically, two sets satisfy mn = 10 and m^2 + n^2 = 29: m = 5 and n = 2 (or vise-versa) and m = - 5 and n = -2 (or vise-versa). The first set gives m + n = 7, while the second one gives m + n = -7.
The problem with your solution is that from (1)+(2) we can get that (m + n)^2 = m^2 + 2mn + m^2 = 29 + 20 = 49. But from this m + n could be both 7 and -7.
Hope it's clear.
Can I conclude that DS need a particular answer and if we don't have that we can't select either of Above 4 options?
Posted from my mobile deviceThere are two types of data sufficiency questions:
1. YES/NO DS Questions:
In a Yes/No Data Sufficiency questions, statement(s) is sufficient if the answer is “always yes” or “always no” while a statement(s) is insufficient if the answer is "sometimes yes" and "sometimes no".
2. VALUE DS QUESTIONS:
When a DS question asks about the value of some variable, then the statement(s) is sufficient ONLY if you can get the single numerical value of this variable.
This question is a VALUE question, so a statement to be sufficient it should give the single numerical value of m + n.
Hope it's clear.