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4=3... Where did I go wrong?


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9 replies to this topic

#1 mewminator

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Posted 25 October 2011 - 06:51 PM





Begin with a simple algebraic equation:
a + b = c

Now, replace each letter with 4 of that letter minus 3 of that letter:
4a - 3a + 4b - 3b = 4c - 3c

Rearrange, so that the 4s are on the left and the 3s on the right
4a + 4b - 4c = 3a + 3b - 3c

Simplify by factoring:
4(a + b - c) = 3(a + b - c)

Then divide each side by a+b-c:
4 = 3

Can someone point out the mistake? (an easy one for maths lovers)
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#2 phillip1882

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Posted 25 October 2011 - 06:56 PM

Spoiler for simple

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#3 Thalia

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Posted 25 October 2011 - 10:36 PM

Lol. I think I've seen a variation on this one. . . and the consequences such as this:
Spoiler for The URL contains TMI if you didn't read the other spoiler.
^_^

Edited by Thalia, 25 October 2011 - 10:37 PM.

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#4 smarts

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Posted 26 October 2011 - 09:16 PM

lol, that was really good, i'm going to use that
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#5 mewminator

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Posted 26 October 2011 - 10:03 PM

lol, that was really good, i'm going to use that

to fool the non-mathematical variety of people XD
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#6 j_arpit

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Posted 15 November 2011 - 09:52 AM

another version:

1. a = b
2. a2 = ab (multiplying a on both sides)
3. a2 - b2 = ab - b2 (subtracting b2 from both sides)
4. (a+b)(a-b) = b(a-b)
5. a+b = b (divided both sides by (a-b) )
6. 2b = b ( from equation 1 i.e. replacing a=b)
7. 2 = 1
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#7 Finix

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Posted 16 November 2011 - 08:12 AM

Good one
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#8 Morningstar

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Posted 22 November 2011 - 12:41 AM

I like these ones. Sometimes it's better when the equations are more complicated because it hides the division by zero. Good puzzle!

Edited by Morningstar, 22 November 2011 - 12:42 AM.

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The cake is a lie.

#9 Swaraj

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Posted 16 December 2011 - 10:06 AM

Run Time exception : DIVIDE BY ZERO
a+b=c => a+b-c = 0
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#10 Rajpoot Sambhavi Singh

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Posted 24 December 2011 - 01:21 AM

good puzzles
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