Who Discover That?

[MatheusMkalo]

http://img3.imageshack.us/img3/8660/aassa.png (http://img3.imageshack.us/i/aassa.png/)

Who discover that?

[tiny-tim]

Hi MatheusMkalo! Welcome to PF! :smile:

That's the same as (A + B)(A - B) = A2 - B2 …

I think that it was known to the ancient Greeks.

[micromass]

There has reportedly been some discussion among scholars whether the Egyptians knew the formula a^3-b^3=(a-b)(a^2+ab+b^2).

In fact, the Babylonians knew formulas like xy=\frac{(x+y)^2-(x-y)^2}{2}. So it wouldn't seem unlikely that already the Babylonians and the Egyptians knew about (a+b)(a-b)=a^2-b^2. But, to my knowledge, there is no proof that they did.

But the Greeks almost certainly knew the formula. It seems like one of the things that Pythagoras liked to prove geometrically...

[micromass]

This site: http://www.math.tamu.edu/~dallen/history/babylon/babylon.html explains that the Babylonians probably knew about the formula and used it to generate Pythagorean triples (yes, Pythagoras' theorem was also known to them!)

[coolul007]

The Greeks had rigorous proofs, while other civilizations didn't require proofs, just acceptance.