8. Expand

(a + b)5

a5 + 5a4b + 10a3b2 + 10 a2b3 + 5ab4 +b5

Each term has degree 5. Start with   a5,   and each successive term has one less factor of   a   and one more factor of   b   until you get to   b5.   The coefficients come from the 5th row of Pascal's triangle.