Use the binomial theorem to expand (a + b)6. 6C0a6 + 6C1a5b + 6C2a4b2 + 6C3a3b3 + 6C4a2b4 + 6C5ab5 6C0a6b + 6C1a5b2 + 6C2a4b3 + 6C3a3b4 + 6C4a2b5 + 6C5ab6 + 6C6b7 6C0a6 + 6C1a5b + 6C2a4b2 + 6C3a3b3 + 6C4a2b4 + 6C5ab5 + 6C6b6