mikegarrison

Do you guys know Bertrand Russell's proof that if 2+2=5 then he was the Pope?

2+2=5 -> 4=5 -> 1=2 -> 2=1

The Pope and Russell were two men. Since 2=1, then they were one.

tof

Set two variables equal..................... a=b
Multiply both by a........................a**2=ab
Subract b squared from both.......a**2 - b**2 = ab - b**2
Factor............................................ .......b(a-b) = (a+b) x (a-b)
divide both by (a-b)...............................b = a + b
a = b so therefore.................................b=b+b
or................................................ ........2b=b
or................................................ .........2=1

mikegarrison

Cute, but of course when you divide by (a-b) you are dividing by zero, which leads to an undefined result.

MsPerky

^ I is confused... Please don't confuse me with the facts.

S1997

Russell's paradoxes are fun. One illustration claims that iff the village barber shaved all the men in the village who didn't shave themselves, he <factually> both shaved himself -- and didn't. Language games...

gomarlins3

I am confused, but that's just my opinon. My students may think it is a fact though.

tof

Well spotted, Mike. I didn't expect anybody to spot the exact flaw so quickly. It took my High School algebra teacher about 5 minutes to get it. (Or had you seen it before?)

timdonna1

Just a quick snippet, 'opinions are like a$$holes, everybody has one'.

mikegarrison

I spent some time looking at the "Factor" line and noticed that it reduced to zero = zero. But that's still legit. Then I realized the real problem was on the next line.

boltonblue

come on he is an engineer after all
if we can't spot this kind of manipulation in a joke we're screwed in practice when the math is much more obscure.