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Math Help - prove answer is wrong given a formula

  1. #1
    Senior Member Mukilab's Avatar
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    prove answer is wrong given a formula

    Hi, my friend gave me this to solve

    Care to help me here, this can't be right?
    Given: a=b

    aČ=a.b
    aČ-bČ=ab-bČ
    (a+b)(a-b)=b(a-b)
    (a+b)=b
    a+a=a
    2a=a
    2=1
    Am I right in saying this does not compute? (a+b)(a-b)=b(a-b)
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  2. #2
    Junior Member
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    the problem is the cancellation, since a=b, a-b is zero and you cant divide (cancel) by zero
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  3. #3
    Senior Member Mukilab's Avatar
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    Quote Originally Posted by emathinstruction View Post
    the problem is the cancellation, since a=b, a-b is zero and you cant divide (cancel) by zero
    I thought this wase too minor, nevermind, I shall pass the news along, just wanted to check
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