2) (-3)⁻³ - (1/2)⁻⁴ = -1/3³ - 2⁴ = -1/27 - 16 = -1/27 - 432/27 = -433/27 = -16 1/27;
4) (2/7)⁻³ + (-2)⁻⁵ = (7/2)³ + 1/(-2)⁵ = 343/8 - 1/32 = 1372/32 - 1/32 = 1371/32 = 42 27/32.
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