Can you?

Let a = b.
Then we multiply by "a" both sides:
a^2 = ab.
We add a^2:
a^2 + a^2 = a^2 + ab <=>
2a^2 = a^2 + ab
Minus 2ab:
2a^2 - 2ab = a^2 + ab - 2ab <=>
2a^2 - 2ab = a^2 - ab
This can also be written as:
2(a^2 - ab)=1(a^2 - ab)
and cancelling (a^2 - ab) from both sides gives us:

2 = 1

Can you find the mistake?

 

I'm not going to respond to this Post because i'm in the RP zone lol!but if i was here i'd say i don't know.I like your new problematic posts angle toshi.It's better than your racist jokes angle.

 

Hmm, that's hard >_< But I think that's the error (Underlined). There isn't a "-2ab", there's just an "a^2" + "ab", the same thing that we have in red. So, if a "2a^2" is equal of an "a^2" + "ab", at the end, in blue, I think there's not a "-", but a "+", so:

2(a^2 - ab)=2(a^2 + ab)

I think that the "-2ab" there isn't.

 

Actually, no. There is nothing wrong with what you have underlined, I deduct (I'm not sure if that's the right word; you know, remove, minus.) "2ab" from both sides not only from the first. You can't do anything only in one side, you must do it in both.

 

Uhh.... 2 doesnt equal 1 =P
*Too lazy to think*

 

Aah, ok XP I will try again later :)

 

You can't cancel with (a^2-ab) because thats the same thing in the equation. To cancel it out, it would have to be (-a^2+ab) or something like that.

Right...?

 

Nope... I cancel them because they're the same. If I divide by (a^2-ab) both sides, the first side will have 2*1 and the second side will have 1*1. Thus 2 = 1

 

hmmm....

Then when you said 2a^2-2ab= a^2-ab can also be written as 2(a^2-ab)=1(a^2-ab) is wrong because to get the 2 and the 1 you have to factor those out of the equation. And you didn't factor it out properly. On the first half, 2a can be factored out of 2a^2 and 2ab while you only factored out a 2.

So technically it would be a-b.

Then a can be factored out of the second part so it would be a-b

Which means the thing would be a-b=a-b

o.o Thats too much math and its probably wrong =/

 

Dude. 2ab=2a^2.

 

Nope. There's no need to factor everything that can be factored. I factored only 2, which can be done.

Not exactly, but close. There's nothing wrong with this. In one step I did something that cannot happen.
I hope you've found it by the time I come back tomorrow.

 

What I meant was. When you subtracted you left it like this:

2a^2 - 2ab = a^2 - ab

Not cool. 2a^2=2ab thus 2a^2 - 2ab = 0 and a^2 - ab = 0 also, because a=b so a^2=ab meaning your last step was entirely fucked.

 

This thread is awesome. It's another mindgasm for me.

 

Yay for mindgasming 8D
Dude, I remember that now. =]]]

 

But what is forbidden there? Can you tell?

 

i think its that A and B cane equal the same thing other wise it would be a^2 = a squared...

 

It's true but that has nothing to do with the fallacy.
C'mon guys you're almost there, do some logical thinking and you'll find the mistake.

 

Okay. If you need me to say it explicitly. You have a 2 and a 1 in front of zeroes in your last step. You say you can nix the zeroes that are multiplying the 1 and 2. The 2 and 1 shouldn't even be there because it's proven that the two are 0=0 the step before meaning it's over there. That's what I said last time. So 0=0 =/= 1=2. Is that specific enough?

 

Yes, very specific but even though, I proved that 1=2. Why should your thinking be true and not mine? You're right but you haven't stated clearly what forbidden step I did. It's the most forbidden thing in maths. Know what I'm saying?
You've said the 99% of the answer but you're stuck in there!