1+1=1?

Anders Englund

Second Unit
Joined
Jun 29, 1999
Messages
426
An oldie, but fun:

a = 1
b = 1


This gives us:
a = b

Now multiply both sides by a:
aa = ab
a^2 = ab

Subtract both sides by b^2:
a^2 - b^2 = ab - b^2

The conjugate rule now gives us:
(a + b)(a - b) = ab - b^2

Extract b on the right side:
(a + b)(a - b) = b(a - b)

Divide both sides by (a - b):
a + b = b

or in other words:
1 + 1 = 1



--Anders
 

Morgan Jolley

Senior HTF Member
Joined
Oct 16, 2000
Messages
9,378
You're not supposed to divide by variables for the reason illustrated above. In the step:
Extract b on the right side:
(a + b)(a - b) = b(a - b)

Divide both sides by (a - b):
a + b = b
(a - b) is equal to 0, which means that dividing both sides by 0 would give you an undefined value on both sides. So you haven't done anything special, just broken fundamental rules.

Man, I love math too much.
 

Mat_M

Stunt Coordinator
Joined
Jan 3, 2003
Messages
225
Yep, can't divide by zero...I had a math teacher try to pull this on my back in the day, but a few of us caught him.
 

Alex Spindler

Senior HTF Member
Joined
Jan 23, 2000
Messages
3,971
I had a 1+1=1 situation once. Formatting in excel was showing .5 + .5 = 1 as 1 + 1 = 1 because of rounding.
 

MikeAlletto

Senior HTF Member
Joined
Mar 11, 2000
Messages
2,369
The company I used to work for had an ad poster that had:

1+1+1+1=1

It was supposed to mean something and spent thousands and thousands of dollars on some ad company to come up with it, but in the end even the employees never understood what the point was.
 

Max Leung

Senior HTF Member
Joined
Sep 6, 2000
Messages
4,611
If you didn't know the values of a and b, and you were given a + b = b, it is clear that a and b both cannot be one. In fact, a has to be equal to zero.

We have:

a + b = b

If we want to know what a is, we must subtract b from both sides:

a + b - b = b - b

Therefore:

a = 0
 

Steven K

Supporting Actor
Joined
Jan 10, 2000
Messages
830
Little Timmy took a drink
But he'll drink no more
Cause what he thought was H2O
Was H2SO4
 

Wayne Bundrick

Senior HTF Member
Joined
May 17, 1999
Messages
2,358
Uh, you're in the wrong classroom. This is math. Chemistry is down the hall. Just follow your nose, the seniors are making stinkbombs.
 

James T

Screenwriter
Joined
Aug 8, 1999
Messages
1,643
We had to do questions similar to 1+1=1 in a Proofs class.

Another question we had on a test was this:

Is it believable that a three-legged chicken can talk?
 

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