I am looking for a trick math equation to where 3 = 1 like the trick math equation where 2 equals 1.

If you're taking it as the thread that Nestorian made some last year, well, you can have any sort of thing...

I'll take a chemistry example, regarding molecules.



There you end up with:

2 + 2 + 1 = 2

:p

These are called 'mathematical fallacies'.

Google that and you will find many.

Here's one: it actually "proves" that 1 = - 1, but if you then add 2 to both sides you get 3 = 1:



Take the square root of both sides (yes - it is perfectly OK to take the square root of a negative number):



Since :



Now cross multiply, using the rule for fractions that if a/b = c/d, then ad = cb:



Since :
1 = -1

And add 2 to both sides:

1+2 = -1+2
3 = 1

QED

Do you see where the fallacy is?

I would say... because this can take either of

Is that it? :)

Quote:

---

Originally Posted by Unknown008

I would say... because this can take either of

Is that it? :)

---

You're saying that ? So if we simply chose that would fix it. True enough. But there's actually an error that occurs earlier in the "proof."

Well, I had suspicion about the



But I wasn't sure. This is the only thing that I don't think might be 'legal'.

Quote:

---

Originally Posted by Unknown008

Well, I had suspicion about the



But I wasn't sure. This is the only thing that I don't think might be 'legal'.

---

Nothing wrong with that - both sides equal -1, right?

Keep looking...

Or is it because you got



You have in fact,

I don't know much about complex numbers, but cross multiplication might not be something allowed.. (taking only the positive root, for the time being)

Quote:

---

Originally Posted by Unknown008

Or is it because you got



You have in fact,

I don't know much about complex numbers, but cross multiplication might not be something allowed... ? (taking only the positive root, for the time being)

---

Tha's it! Using the notation , the left hand side is:



and the right hand side is



So the error is:

for negative numbers.

Finally! Thanks! :)