absolute value

[mehrasa]

is M<0?
1) -M= absolute value of M
2) M^2=9

[spoiler]OA: C but I think A is sufficient[/spoiler]

[shankar.ashwin]

M could be 0 here. Hence C

[neelgandham]

Is M<0?

1) -M = absolute value of M

=> -M = |M| => M <=0 (|M| is always a positive number or 0, for -M to be a positive number or 0, M should be a negative number or a 0) Hence insufficient.

2) M^2=9

=> M = -3 or + 3, Insufficient

[spoiler]Option 1 + 2 ==> M = -3 Sufficient Option C[/spoiler]

[mehrasa]

Is M<0?

1) -M = absolute value of M

=> -M = |M| => M <=0 (|M| is always a positive number or 0, for -M to be a positive number or 0, M should be a negative number or a 0) Hence insufficient.

2) M^2=9

=> M = -3 or + 3, Insufficient

[spoiler]Option 1 + 2 ==> M = -3 Sufficient Option C[/spoiler]

thanx for ur reply... but to me, when a No. come out of absolute value negative(as Statement 1 says) that the number is negative ==> M should be negative... why u are saying that M can be negative or ZERo???????????

[Brent@GMATPrepNow]

thanx for ur reply... but to me, when a No. come out of absolute value negative(as Statement 1 says) that the number is negative ==> M should be negative... why u are saying that M can be negative or ZERo???????????

Statement 1 tells us that: -M = |M|
There are two possible conclusions here:
a) M is negative. For example, if M=-2, we get -(-2) = |-2| TRUE
b) M is zero. If M=0, we get: -0 = |-0| TRUE

Cheers,
Brent