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Half the posts over here are trying 2 prove that 1=2 or 0=-1 or

  1. Jul 14, 2005 #1
    half the posts over here are trying 2 prove that 1=2 or 0=-1 or sumthing like that lol so i thought ill try sumthing of that sort too...its silly...but it fascinated me when i was in class 8.

    Let a = b where a, b are any 2 real numbers
    a^2 = ab
    a^2-b^2=ab-b^2
    (a-b)(a+b)=b(a-b)
    a+b=b
    But a = b therefore b = 2b for any real number b

    enjoy! dont curse me for wasting ur time when u find the mistae!
     
  2. jcsd
  3. Jul 15, 2005 #2
  4. Jul 15, 2005 #3
    a+b=b;
    a=b;
    so b+b=b
    so b=a=0?
     
  5. Jul 15, 2005 #4
    Answer in white:

    "(a-b)(a+b)=b(a-b)"
    a-b=0, so it is meaningless to divide both sides by (a-b)
     
  6. Jul 15, 2005 #5
    Let a = b where a, b are any 2 real numbers

    a2 = ab
    Subtract both sides with b2 ==> a2-b2 = ab-b2
    Simplify ==> (a-b)(a+b)=b(a-b)
    divide with (a-b) ==> a+b = b
    a=b gives ==> 2b = b

    And the error is as said very simple.
     
  7. Jul 15, 2005 #6
    to get eq. (2) from eq. (1)

    you have to divide both sides by (a-b)
    since a=b
    therefore, (a-b)=0...

    in addition, you have divided two sides by zero...

    a number divided by zero is undefined in math...

    got ya!
     
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