Jonas J�rgensen wrote: > Bamm Gabriana wrote: > > > It is. > > > > Let a = 1. > > a^2 = a (multiply both sides by a) > > a^2 - 1 = a - 1 (subtract 1 from both sides) > > (a + 1)(a - 1) = (a - 1) (factor it) > > (a + 1) = 1 (cancel common factors) > > 1 + 1 = 1 (substitution.) > > > > QED/ :) > > 1 + 2 = 3. Ergo 4 + 5 = 6. > > /Jonas
Prove that (a + b) (a - b) = a^2 - b^2 a * a = a^2 + * - = - b * b = b^2 QED
