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If the function e –x f(x) assumes its minimum in the interval [0,1] at x = 4 1 , which of the following is true ?

f '(x) < f(x), 4 3 x 4 1 < <
f '(x) > f(x), 4 1 x 0 < <
f '(x) < f(x), 0 < x < 4 1
f '(x) < f(x), 4 3 < x < 1

Correct answer: f '(x) < f(x), 0 < x < 4 1

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