Binomial Theorem/Abel's Generalisation/Proof 1

Proof
By admitting $y = \left({x + y}\right) - x$, we have that:
 * $\left({x + y}\right)^n = \left({x + \left({x + y}\right) - x}\right)^n$

Expanding the in powers of $\left({x + y}\right)$: