Answer:
2187 + 5103d + 5103d² + 2835d³ + 945d⁴ + 189d⁵ + 21d⁶ + d⁷
Step-by-step explanation:
(d + 3)⁷
7C0×3⁷×d⁰ + 7C1×3⁶×d¹ + 7C2×3⁵×d² + 7C3×3⁴×d³ + 7C4×3³×d⁴ + 7C5×3²×d⁵ + 7C6×3¹×d⁶ + 7C7×3⁰×d⁷
= 2187 + 5103d + 5103d² + 2835d³ + 945d⁴ + 189d⁵ + 21d⁶ + d⁷
