> 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/ :)




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