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Find the principle fourth root of -81, checking your answer by raising to the 4th power. If there are "no real roots," then type: NONE

Find the principle cube root of -27, checking your answer by cubing (raising to the 3rd power). If there are "no real roots," then type: NONE

Find the principle square root of 4/25. Give your answer as a fraction in simplest form (numerator, then "/", then denominator). If there are "no real roots," then type: NONE