Original: ( x + y ) ^ n & = { n choose 0 } x ^ n y ^ 0 + { n choose 1 } x ^ { n-1 } y ^ 1 + { n choose 2 } x ^ { n-2 } y ^ 2 + { n choose 3 } x ^ { n-3 } y ^ 3 + cdots
Simplified: ( 3 +2 x ) ^ 2 = 1 cdot 3 ^ 2 cdot ( 2x ) ^ 0 + 2 cdot 3 ^ 1 cdot ( 2x ) ^ 1 + 1 cdot 3 ^ 0 cdot ( 2x ) ^ 2 = 9 + 12x + 4x ^ 2