> It is. > > Let a=b. > 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/ :)
Oops, I meant: 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/ :)