Start with: -20 = -20
Which is the same as: 16-36 = 25-45
Which can also be expressed as: (2+2) 2 (9 X (2+2) = 52) 9 X 5
Add 81/4 to both sides: (2+2) 2 (9 X (2+2) + 81/4 = 52) 9 X 5 + 81/4
Rearrange the terms: ({2+2}) 9/2) 2 = (5-9/2) 2
Ergo: 2+2 - 9/2 = 5
Hence: 2 + 2 = 5

See... simple, isn't it?

i found this in some mathematical article ,i saved some others tooo

Arun Giridharan wrote:Start with: -20 = -20
Which is the same as: 16-36 = 25-45
Which can also be expressed as: (2+2) 2 (9 X (2+2) = 52) 9 X 5
Add 81/4 to both sides: (2+2) 2 (9 X (2+2) + 81/4 = 52) 9 X 5 + 81/4
Rearrange the terms: ({2+2}) 9/2) 2 = (5-9/2) 2
Ergo: 2+2 - 9/2 = 5
Hence: 2 + 2 = 5

See... simple, isn't it?

i found this in some mathematical article ,i saved some others tooo

Your equations as written don't make much sense to me. Could you clarify them a bit?

Usually I've found that similar problems are due to division by 0, but again, I can't follow your math to see if this is the case here.

I think that you may have copied it wrong, because some of your transitions don't make sense. You are missing operators with some, and you added parens around the equals that compare the both sides.

This is actually a common trick (although not as common as divide by zero). The trick relies on the fact that the square root has a positive *and* negative result -- and basically obfuscates the fact that they are taking the positive number in one case, and the negative number in the other.

Henry Wong wrote:
This is actually a common trick (although not as common as divide by zero). The trick relies on the fact that the square root has a positive *and* negative result -- and basically obfuscates the fact that they are taking the positive number in one case, and the negative number in the other.

Henry

I'm curious...
We seem to see a handful of these "proofs" each year. Does anyone here still believe there are simple algebraic ways to prove that two unequal constants are equal?

I'll admit that sometimes it's a fun challenge to determine which one is the invalid step in a new "proof". I'm with Arun... this kind of thing may deserve a or maybe a , but I certainly don't think it deserves a , as some have gotten.