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AbdulRehman

  • 3 years ago

Why (-)*(-)=(+).

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  1. amistre64
    • 3 years ago
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    hmmm....... multiplication is adding really if you add the opposite of 3 that opposite of 5 times we get what?

  2. amistre64
    • 3 years ago
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    the opposite of 3; 5 times = -3 -3 -3 -3 -3 = -15 so the opposite of 5 times gets you to 15

  3. amistre64
    • 3 years ago
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    -(-3)-(-3)-(-3)-(-3)-(-3) = 15

  4. amistre64
    • 3 years ago
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    does that make sense?

  5. AbdulRehman
    • 3 years ago
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    it takes me to other sense that is (-1)*x=1 then x=(-1)

  6. nowhereman
    • 3 years ago
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    Do you understand / accept (-1)*(1) = -1 ?

  7. AbdulRehman
    • 3 years ago
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    yeah

  8. nowhereman
    • 3 years ago
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    So then you get \[0 = 0\cdot 0 = (a-a)\cdot(b-b) = (a+(-a))\cdot(b+(-b))\]so using distributivity\[ = a\cdot b + a\cdot (-b) + (-a)\cdot b + (-a)\cdot(-b) = a\cdot b - a\cdot b - a\cdot b + (-a)\cdot (-b)\]thus altogether \[ 0= (-a)\cdot(-b) - a\cdot b\] and that means nothing else than \[(-a)\cdot(-b) = a\cdot b\]

  9. amistre64
    • 3 years ago
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    phhhhbbbtttt!!! how needs proofs ;)

  10. nowhereman
    • 3 years ago
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    hehe, Mathematics needs it, or from a certain point on anything will be arbitrary because you can't tell intuitively what's true and what's false.

  11. nowhereman
    • 3 years ago
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    btw 555 medals, awesome work there :-)

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