а) 2⁻² + 3⁻¹ = 1/2² + 1/3¹ = 1/4 + 1/3 = 3/12 + 4/12 = 7/12
б) (-3)⁻² + (-2)⁻³ = 1/(-3)² + 1/(-2)³ = 1/9 - 1/8 = 8/72 - 9/72 = - 1/72
в) (-5)⁻² + 6⁻¹ = 1/(-5)² + 1/6¹ = 1/25 + 1/6 = 6/150 + 25/150 = 31/150
г) (-2/3)⁻³ + 4⁻² = (-3/2)³ + 1/4² = -27/8 + 1/16 = -54/16 + 1/16 = -53/16 = -3 целых 5/16