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K) → $ \sqrt[5]{1024} = \sqrt[5]{2^{10}} = 2^{\frac{\cancel{10}^2}{\cancel5_1}} = 2^2 = 4;$
L) → $ \sqrt[3]{625} =\sqrt[3]{5^4} = 5^{\frac{4}{3}};$
M) → $ \sqrt[3]{121^2} = \sqrt[3]{11^{2×2}} = \sqrt[3]{11^4} = 11^{\frac{4}{3}};$
N) → $ \sqrt[7]{-(9)^2} = -(9)^{\frac{2}{7}}.$