What did you learn today?

If you let a = 1 and b = 1, then a = b.
Then for fun, multiply a to both sides, (a)(a) = (a)(b).
Then subtract b^2 from both sides, a^2 - b^2 = ab - b^2.
Then factor both sides, (a - b)(a + b) = b(a - b).
Simplify, a + b = b.
Substitute a = b: b + b = b
b + b = b
2b = b
2 = 1.

I('m) learned/ing to apply math to practical things... and learned/ing everything that's possible by dividing by zero.

But stating 2=1 does not make mathematical sense and therefore is not true 0_o

2=/=1 as we all know, but i guess there's a whole bunch of random crap that we can do in math to prove someone else wrong ...