Question: In how many ways can 3 friends be seated in a row of 5 chairs?
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Question: In a right triangle, if the length of the hypotenuse is 10 cm and the adjacent side measures 6 cm, what is the value of the cosine of the angle between them?
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Find the derivative of f(x) = 3x^4 - 2x^3 + 5x^2 - 6x + 1.