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Number Properties (Guide 1). Chapter 5. Question #7 on P. 71

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mjharv
 Post subject: Number Properties (Guide 1). Chapter 5. Question #7 on P. 71
 Post Posted: Sun Jul 25, 2010 6:11 pm 
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Students


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I'm a bit confused here. Shouldn't the answer be 20 (as opposed to -12).

In the explanation -2^4 is said to work out to -16... shouldn't it be positive 16?

So instead of 4-16=-12... shouldn't you have 4+16=20?


(Sorry, and in case it wasn't clear, this refers to the 4th edition of the Numbers Properties book.)
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tim
 Post subject: Re: Number Properties (Guide 1). Chapter 5. Question #7 on P. 71
 Post Posted: Sat Sep 04, 2010 4:31 pm 
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ManhattanGMAT Staff


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Location: Southwest Airlines, seat 21C
No, you do the exponent before the minus sign. 2^4 is 16, then we apply the minus sign to get -16. i think what you had in mind was (-2)^4. When we take the negative first (which requires parentheses), the answer is indeed 16..

Of course, the problem you refer to doesn't seem to have anything to do with the question you've asked, but i hope this helps anyway..

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Tim Sanders
Manhattan GMAT Instructor
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