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 June 26th, 2011, 11:29 PM #1 Newbie   Joined: Jun 2011 Posts: 20 Thanks: 0 why the product of two negative integers is positive because the multiplication operation is a repeated addition operation for example (-3) x (-2) = - ( 3 x -2 ) = - ( (-2) + (-2) + (-2) ) = - (- 6 ) = 6 and 6 is positive integer to view all topics visit my blogger http://imaginemath.blogspot.com/
 June 26th, 2011, 11:34 PM #2 Senior Member   Joined: Apr 2007 Posts: 2,140 Thanks: 0 Let a be positive and b be negative. ab < 0 is correct. Since -a is negative, multiplying both sides of the inequality by -1 gives -ab > 0.
 June 26th, 2011, 11:49 PM #3 Newbie   Joined: Jun 2011 Posts: 20 Thanks: 0 Re: why the product of two negative integers is positive yes johnny
 June 27th, 2011, 02:23 AM #4 Senior Member     Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 521 Math Focus: Calculus/ODEs Re: why the product of two negative integers is positive 1 = (1)(1) 1 = (1)(1) + 0 1 = (1)(1) + 0(-1) 1 = (1)(1) + (1 - 1)(-1) 1 = (1)(1) + (1)(-1) + (-1)(-1) 1 = (1)(1 - 1) + (-1)(-1) 1 = (1)(0) + (-1)(-1) 1 = (-1)(-1)
 June 27th, 2011, 02:46 AM #5 Senior Member   Joined: Sep 2010 Posts: 101 Thanks: 0 Re: why the product of two negative integers is positive then by your assumption: (-3)*2=-6 (-3)*(-2)=-6 2=-2 ???
 June 27th, 2011, 11:02 AM #6 Newbie   Joined: Jun 2011 Posts: 6 Thanks: 0 Re: why the product of two negative integers is positive We can carry out the experiment. Take a piece of paper - it will be our first plane. Draw a line from north to south, this we will create two planes-western and eastern (- and +).All with the sign (-) is the property of western plane , sign (+) means that all it belong to east plane. Now draw the same squares in each plane and find their area. If you use negative values ??of length and width in the western plane you get ONLY plus value areas- but this is wrong (in our case)!!! Why is this not correct? Because the plus value of the area, are the property east of the plane. One value of length or width should be (-) and one (+) in western plane. My thoughts ...
 June 27th, 2011, 02:45 PM #7 Newbie   Joined: Jun 2011 Posts: 20 Thanks: 0 Re: why the product of two negative integers is positive it is really wonderful job
June 28th, 2011, 05:22 PM   #8
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Quote:
 Originally Posted by filipd by your assumption
What assumption?

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