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Where did this proof go wrong?

I found it at the link below, but here it is. Have the laws of math failed us?

Theorem: 3=4

Proof:

Suppose:

a + b = c

This can also be written as:

4a - 3a + 4b - 3b = 4c - 3c

After reorganizing:

4a + 4b - 4c = 3a + 3b - 3c

Take the constants out of the brackets:

4 * (a+b-c) = 3 * (a+b-c)

Remove the same term left and right:

4 = 3

http://www.ahajokes.com/m003.html

Update:

Interesting that just the possibility of a variable being 0 can mess up the math.

Thanks all,

Doug

7 Answers

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  • 9 years ago
    Favorite Answer

    In the last step, you wrote "Remove the same term left and right.". But that is only a meaningful mathematical operation, if the term is not equal to zero. In your proof, it is equal to zero. So you are effectively trying to divide by zero.

    This is just another example why dividing by zero is not allowed in math.

    Otherwise, I could just do it like this:

    4 * 0 = 3 * 0

    Remove the same term left and right:

    4 = 3

  • 9 years ago

    The error is that a + b - c = 0.

    c = a + b

    a + b - c = a + b - (a + b) = 0

    4 * 0 = 3 * 0

    Your error is that you have hidden where you are multiplying by 0.

    Your greater error is that, instead of trying to do something useful and creative with math, you are trying and failing to prove yourself cleverer than Y!A users.

  • 9 years ago

    (a + b - c) = 0

    4(0) = 3(0)

  • 5 years ago

    "tolerance to variety is at as quickly as on the subject count number of a persons' distance from it" Its easy for those so called liberals ( hypocrites) in Vermont, Maine, New Hampshire, etc....to be "tolerant" while the priority of minorities comes up because of the fact maximum of them do no longer might desire to stay among them or be plagued via the crime they reason. i understand some that have honestly by no skill even spoken to a black person greater effective than a pair of times of their lives ( mutually as on trip ) yet they're rapid to show the accusation of racism at somebody like me that lives in south east Georgia in a community this is 60% black........I wager you in the event that they moved to the place I stay they could discover out that they do no longer seem to be as liberal and tolerant as they are asserting they're...fact! gay marriage is something they could honestly might desire to renowned on the ingredient of homestead if it the place allowed...Hmmmmmm they have a great form of those "noble" and "inventive" suggestions of their empty heads till it is going to consequence THEM in my view.......then they instruct their genuine hues! LOL mutually as i do no longer in my view approve of homosexuality as a Libertarian I help their proper to have civil unions ( no longer marriage because of the fact this is a non secular employer ) and all the rights of straight couples.....i'm surprised at those so called "inventive" states that are no longer training what they carry forth..... and Im the illiberal one? LOL

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  • fizixx
    Lv 7
    9 years ago

    wtf

    What is this...Obama math?

    This doesn't make ANY sense at all.

    HOW do you justify this step???

    4a - 3a + 4b - 3b = 4c - 3c

  • Anonymous
    9 years ago

    This silly thing is hundreds of years old.

    "remove" a term? WTF does that mean, do you suppose?

    Which law exactly, deals with "removing" terms?

  • 9 years ago

    after reorganzing i got a+b=c so idk

    Source(s): .
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