Answer:
a⁴ + 20a³ + 150a² + 500a + 625
Step-by-step explanation:
(a + 5)⁴
₄C₀ a⁴ 5⁰ + ₄C₁ a³ 5¹ + ₄C₂ a² 5² + ₄C₃ a¹ 5³ + ₄C₄ a⁰ 5⁴
a⁴ + 4 a³ 5 + 6 a² 25 + 4 a 125 + 625
