Tuesday, August 2

1=0?

The following is a "proof" that one equals zero.

Consider two non-zero numbers (Any number except zero) x and y such that

x = y.
Then x^2 = xy.
Subtract the same thing from both sides:
x^2 - y^2 = xy - y^2.
Dividing by (x-y), obtain
x + y = y.
Since x = y, we see that
2 y = y.
Thus 2 = 1, since we started with y nonzero.
Subtracting 1 from both sides,
1 = 0.

What's wrong with this "proof"?


For you "math majors" out there this should be relatively simple.

7 comments:

daniel said...

Tricky...I had to google-cheat to find out. Since I cheated I won't point it out...good luck Julie/Dona/Other mathematically inclined people...

daniel said...

Oh, and if you get bored after that...this one looks like fun too: http://www-math.mit.edu/~tchow/mathstuff/proof.pdf

Julie said...

We did lots of stuff just like this in abstract algebra. It's not any fun if I just blurt out the answer. I'd like to see what people who haven't been tampered by with books come up with.

Luke said...

Dona's gotten it, but she just told me rather than make a post...which is no fun for the rest of blog land. :)
Sheesh..way to go Dona.
Do like Julie and tell the world!

Anon said...

Iknow!!Iknow!!Iknow!!

Is that better? :)

Luke said...

Well...if we ignore the fact that your exlamation points and your "I's" run together visually...I guess it's better.

Anon said...

just *sniff* can't *sniff* please...