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Order of Operations: Negative Sign, Parenthesis


Date: 8/25/96 at 10:6:23
From: Doug Young
Subject: Meaning of Negative Sign, Parenthesis

Dear Dr. Math,

Every school year my students have a hard time seeing 
(-2)^2 = 4 and -2^2  =  -4.  They do not see the need for the 
( ) and see -4 as a negative number taken to the 2nd power.  

I have tried to show them -1 * 2^2 = -4 is what is being stated
when they see -2^2 = -4. Any suggestions?  

Thank you,
Mrs. Young.


Date: 8/25/96 at 15:30:58
From: Doctor Robert
Subject: Re: Meaning of Negative Sign, Parenthesis

I think that all students have trouble with this one.  You have 
shown them that -2^2 means -1 * 2^2.  What you need to convince 
them to do is to use the ORDER OF OPERATIONS correctly.  

The exponent must be dealt with before the multiplication by -1.  
This is not a law of God, but an international agreement among 
mathematicans.

Good luck.
-Doctor Robert,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/   
    
Associated Topics:
Middle School Algebra

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