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Math Help - Adding and subtracting negatives

  1. #1
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    Adding and subtracting negatives

    ok im confused and its on easy stuff hope this is the correct forum...im into adding and subtracting negatives and its confusing the heck outta me so if you take this equation 8 - -7= i assume on the chart you travel toward the negative side so the answer is 1 ....but the answer is actually adding so my question is this what part of these equations tells you which way to go on the chart ....i thought i should go toward the negatives because of the subtraction sign but in reality i ignore the subtraction sign and add ?
    Last edited by mr fantastic; January 6th 2011 at 01:00 PM. Reason: Re-titled.
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  2. #2
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    Two negatives make a positive.

    So \displaystyle 8 - (-7) = 8 + 7 = \dots.‏
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  3. #3
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    To see why this is true, start at 8 on the number line. If you were to subtract 7, I think you understand that you would move left 7 (to get 1). So to subtract -7 you move right 7 (to get 15). In practice this amounts to changing the two negatives to a positive as ProveIt has already shown.
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