3.
a) (2/3 a⁻⁴ b⁻²)⁻² =( 9/4)*a⁸ b⁴
б) [(5a⁻²)/(6b⁻¹)]⁻² * (10 a³ b⁴) = (36a⁴ * 10 * a³ b⁴) / (25 b²) = 72/5 a⁷ b²
4. (5⁻⁹ * 25⁻²) / (125)⁻⁴ = (5³)⁴ / (5⁹ * 5⁴) = 5¹² / 5¹³ = 1/5
5. (6,8*10⁶)*(4,5*10⁻⁸) = 306*10⁻² = 3,06
6. (a⁻¹ + b)*(a + b⁻¹)⁻¹ = (1/a + b) / (a + 1/b) = (1 + ab)² / ab