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absolute value

by Lattefah84 » Sun Jan 31, 2010 12:06 pm
What is the sum of integers [m]A[/m] and [m]B[/m] ?

1. [m]|A| = -|B|[/m]
2. [m]|B| = -|A|[/m]



* Statement (1) ALONE is sufficient, but Statement (2) ALONE is not sufficient
* Statement (2) ALONE is sufficient, but Statement (1) ALONE is not sufficient
* BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient
* EACH statement ALONE is sufficient
* Statements (1) and (2) TOGETHER are NOT sufficient

In both equations the left side cannot be negative and the right side cannot be positive. Each equation holds only for [m]A = B = 0[/m] . In this case, [m]A + B = 0[/m] .
The correct answer is D.



My question is - isn't I A I = - I B I ; without "absolute" sign A= -B ? Can someone please explain this...
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by sars72 » Sun Jan 31, 2010 12:17 pm
i'm not sure i understand what you are facing difficulties with

you are correct with respects to 0 being the only possbile answer

modulus gives the absolute value, so the only instance where modulus can equal the -ve of a variable is when that variable is the integer 0.

If you are asking can we remove the modulus signs from both sides of the equation by cancelling it out, the answer is NO, we cannot. The modulus sign is an operation and we cannot cancel it out.
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by Lattefah84 » Sun Jan 31, 2010 12:24 pm
sars72 wrote:i'm not sure i understand what you are facing difficulties with

you are correct with respects to 0 being the only possbile answer

modulus gives the absolute value, so the only instance where modulus can equal the -ve of a variable is when that variable is the integer 0.

If you are asking can we remove the modulus signs from both sides of the equation by cancelling it out, the answer is NO, we cannot. The modulus sign is an operation and we cannot cancel it out.
We can't cancel put the absolute valute, so we put I A I + I B I = 0 ?
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by sars72 » Sun Jan 31, 2010 12:30 pm
Lattefah84 wrote: We can't cancel put the absolute valute, so we put I A I + I B I = 0 ?
exactly! so, the only way the sum of two absolute values is equal to 0 is if you have |0| + |0|
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by Lattefah84 » Sun Jan 31, 2010 12:50 pm
sars72 wrote:
Lattefah84 wrote: We can't cancel put the absolute valute, so we put I A I + I B I = 0 ?
exactly! so, the only way the sum of two absolute values is equal to 0 is if you have |0| + |0|
oh thanks, I didn't know about that rule!
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