Math Is Fun Forum

Ashok123

Guest

Re: 1=2 proof

Hey, swim is new here and is wondering if someone could direct him to the classic 1=2 proof? Thanks.

a=a

=

(since, multiply both side with "a")

-

=

-

    (since,

-

=(a+b)(a-b))
(a-a)(a+a)=a(a-a)
a+a=a
2a=a
2=1

anonimnystefy

Real Member

From: Harlan's World

Registered: 2011-05-23

Posts: 16,049

Re: 1=2 proof

Hi Ashok123

Your steps aren't algebraicly correct. How did you get that a^2-a^2=a(a-a) ?

Last edited by anonimnystefy (2012-07-30 21:18:19)

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“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

cmowla

Member

Registered: 2012-06-14

Posts: 70

Re: 1=2 proof

Hi Ashok123

Your steps aren't algebraicly correct. How did you get that a^2-a^2=a(a-a) ?

The only flawed step was when he divided by

.  Everything else is correct.

Last edited by cmowla (2012-07-31 16:45:43)

anonimnystefy

Real Member

From: Harlan's World

Registered: 2011-05-23

Posts: 16,049

Re: 1=2 proof

Hi cmowla

Yes, you are right.

---

“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

careless25

Real Member

Registered: 2008-07-24

Posts: 560

Re: 1=2 proof

Heres an infinite series "proof" that shows 0 = 1

0 = 0 + 0 + 0 + 0 + · · ·
= (1 − 1) + (1 − 1) + (1 − 1) + (1 − 1) + · · ·
= 1 − 1 + 1 − 1 + 1 − 1 + 1 − 1 + · · ·
= 1 + (−1 + 1) + (−1 + 1) + (−1 + 1) + · · ·
= 1 + 0 + 0 + 0 + · · ·
= 1

"Legend has it that, around 1703, in letters to contemporary mathematicians, an Italian monk by the name of Guido Grandi (often called Guido Ubaldus) presented this as proof of the existence of God, since it suggested that the universe could have been created out of nothing! What he actually meant isn't clear, but we do know that the brightest minds of the day were unsure how to explain what the problem was. Leibniz at least recognized that the problem was in the ____ line above;"

I left it blank intentionally

This is copied from my Calculus prof notes, he showed is this "proof" in class.

Last edited by careless25 (2012-08-08 14:42:23)