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Re: For all integers a and b, a # b = –|a + b| [#permalink]
Answer is clearly C
It's an easy question.
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Re: For all integers a and b, a # b = –|a + b| [#permalink]
GREMasterBlaster wrote:
Answer is clearly C
It's an easy question.


easy to get tripped up, since the intergers used are A and B, and the option choices are A and B
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Re: For all integers a and b, a # b = –|a + b| [#permalink]
Since |a|=-a when a<0, Shouldn't we also test for -(-|-10+7|) which gives us 3. Hence it could be -3 or 3 isn't it? Thanks for the clarification.
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Re: For all integers a and b, a # b = –|a + b| [#permalink]
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in a#b you just need to substitute.

a = -10 and b = 7

QA - |a+b|= - |-3|= - |3| (insde the absolute value) = -3

QB is -3

Answer is c
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Re: For all integers a and b, a # b = –|a + b| [#permalink]
I agree with Runnyboy44's doubts about the answer. How are we supposed to know that we do not have to consider the case - -(|-3|) = +3 in this case?

This doubt could be corroborated by looking at exercises where the function is defined as a # b = (+)|a + b|. Then I would seperate between case 1:

a # b = (+)|a + b|

and case 2: a # b = (-)|a + b|

.

how are we supposed to that we should limit our answer strategy to plugging in.
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Re: For all integers a and b, a # b = –|a + b| [#permalink]
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Zamala wrote:
I agree with Runnyboy44's doubts about the answer. How are we supposed to know that we do not have to consider the case - -(|-3|) = +3 in this case?

This doubt could be corroborated by looking at exercises where the function is defined as a # b = (+)|a + b|. Then I would seperate between case 1:

a # b = (+)|a + b|

and case 2: a # b = (-)|a + b|

.

how are we supposed to that we should limit our answer strategy to plugging in.



Hi..

we have to just read the information given in the question while we solve a question.
The question gives us a function a # b = (-)|a + b|...
Now you have to find (-10)#7, this means a=-10 and b=7, so substitute in the function to get (-10)#7=-|-10+7|=-3

|a|=-a when a<0.. But this is true when you do not know the value of a. Here you know what a and b stands for..

Even here a+b=-10+7=-3<0 so |a+b|=-(a+b) when (a+b)<0 thus |-10+7|=-(-10+7)=-(-3)=3..
But we are looking for -(|a+b|), which will be equal to -(3)
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Re: For all integers a and b, a # b = |a + b| [#permalink]
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Re: For all integers a and b, a # b = |a + b| [#permalink]
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