[TLHroolz]

Explain:

a=b
a^2=ab
2a^2=a^2+ab
2a^2-2ab=a^2-ab
2(a^2-ab)=(a^2-ab)
2=1
?????


This was posted from The Student Room's iPhone/iPad App

[Allofthem]

a^2 - ab = 0 by a = b.

[Rahul.S]

this is OLD AND DEAD!

[Piko_Piko]

Wow. You broke Maths. You are now the indisputed master of the universe. How does it feel?

[Slumpy]

I'm amazed people never get tired of this.

[Instincts_2012]

You cannot divide by 0.

Using variables, it would work.

Using real numbers, it will not work.

[Mr_Muffin_Man]

lol i still love that proof even though it isn't really a proper proof it confuses people quite a bit - but it does show why you shouldn't divide by 0

[raheem94]

TROLL

[tamimi]

omg 1.999999999999999999999999999999 9999999999 =2 omg

[Trollin]

(Original post by tamimi)
omg 1.999999999999999999999999999999 9999999999 =2 omg

No, it doesn't.
1.999.... = 2

[Chumbaniya]

(Original post by Instincts_2012)
You cannot divide by 0.

Using variables, it would work.

Using real numbers, it will not work.

I don't understand what you mean by 'using variables, it would work'. You can't divide by a variable which potentially takes the value of zero without branching your reasoning into "either <expression> = 0 or <everything from dividing by the expression onwards>".

[tamimi]

(Original post by Trollin)
No, it doesn't.
1.999.... = 2

[Trollin]

(Original post by tamimi)

Guilty as charged. But seriously, the pedantry of mathematicians knows no bounds :P

[raheem94]

(Original post by tamimi)

does equal

But what the OP has written is nonsense!

[Micky76]

(Original post by raheem94)
does equal

But what the OP has written is nonsense!

I know that is widely accepted but I just can't see it that way. Wouldn't it be true saying:



That's just my thought. But then again, the infinity fraction tends to zero... However that doesn't mean it shouldn't be there.

[raheem94]

(Original post by Micky76)
I know that is widely accepted but I just can't see it that way. Wouldn't it be true saying:



That's just my thought. But then again, the infinity fraction tends to zero... However that doesn't mean it shouldn't be there.

I can't say much about it.

Read this.

[Melikeyflute]

(Original post by As_Dust_Dances_)
You've just assumed a equals b and that's like saying c also equals d which isn't the case!

Lol what?

[clad in armour]

(Original post by Slumpy)
I'm amazed people never get tired of this.

because nobody stops for a second and thinks, they just get overwhelmed by the sheer plausibility and why nobody has seen it yet

[Above.The.Empyrean]

Trifling!

[Dalek1099]

this doesn't work with 0 values a good example is 2x=x (/x) 2=1 2x-x=0 x=0.In the above proof a^2-ab=0 because it is equal to aa-aa=0 and 2 times that will equal 1 times that.