How do you proof that 2 is actually 1?

Answer 1

let a and b be non-zero quantities a=b, multiply through by a a^2=ab, subtract b^2 from both sides a^2-b^2=ab-b^2, factor (a+b)(a-b)=b(a-b), divide both sides by (a-b) a+b=b, a=b so write... 2b=b, divide both sides by b 2=1