BrainDen.com - Brain Teasers
• 0 Question The following is what seems to be a mathematical proof that two equals one. What's wrong with it?

a = b

aa = ab

aa - bb = ab - bb

(a + b)(a - b) = b(a - b)

a + b = b

a + a = a

2a = a

2 = 1

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• 0 how do you go from.........a + b = b

to........a + a = a

the top line just means a=0?

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• 0 a must equal zero right?

aargh confusing much ??

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• 0 how do you go from.........a + b = b

to........a + a = a

the top line just means a=0?

Because a = b, he can substitute a and b freely for each other.

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• 0 The following is what seems to be a mathematical proof that two equals one. What's wrong with it?

a = b

aa = ab

aa - bb = ab - bb

(a + b)(a - b) = b(a - b)

a + b = b

a + a = a

2a = a

2 = 1

The problem is with the division in the fourth line. You have to divide each element on the left side of the equation by (a-b). The fifth line should be (a+b)/(a-b)=b

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• 0 The problem is with the division in the fourth line. You have to divide each element on the left side of the equation by (a-b). The fifth line should be (a+b)/(a-b)=b

You got it wrong, brother. The division was ok in a sense, you divide both the left and right sides by the same number other than zero. The problem here is dividing both sides -- the left and right sides -- by zero. From basic maths we know that when a number is divided by zero, it would be undefined.

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• 0
You got it wrong, brother. The division was ok in a sense, you divide both the left and right sides by the same number other than zero. The problem here is dividing both sides -- the left and right sides -- by zero. From basic maths we know that when a number is divided by zero, it would be undefined.

I'll bet Aunt Minta is probably a sista. Share on other sites
• 0 I'll bet Aunt Minta is probably a sista. Thanx Bonanova, I agree. I just didn't notice the name. What do you think the odds would be that Auntie is a man?

Edited by brhan

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