**Proof.**

```
a + bc = (a'(bc)') ADD
= (((a'b')'(a'c')')')' DIST
= ((a'b')'(a'c')')" rewrite
= (a'b')'(a'c')' DN
= (a + b)(a + c) ADD
EXCL N(ab)' ↔ Na' ∧ Nb'
(Exclusion) -
```