24.2. ⁵√4² * √4 = ⁵√(2²)² * 2 = ⁵√2⁴ * 2¹ = ⁵√2⁴⁺¹ = ⁵√2⁵ = 2^5/5 = 2

25.2. (∛4 — ∛10 + ∛25)(∛2 + ∛5) = (∛2)³ + (∛5)³ = (2^1/3)³ + (5^1/3)³ = 2 + 5 = 7

26.2. (√20 + √80) : √5 = 6√5 : √5 = 6

27.2. a² + a^-2 a + a^-1 = 5
a² + 2 * a * a^-1 + a^-2 = 25
a¹ * a^-1 = a^1-1 = a⁰ = 1
a² + a^-2 + 2 = 25
a³ + a^-2 = 25 — 2 = 23