30   12. The function f is defined by f(x) = e3 2 4 x x k + where k is a positive constant. (a) Show that fʹ(x) = (12x 2 − 8x + 3k) g(x) where g(x) is a function to be found. (3) Given that the curve with equation y = f(x) has at least one stationary point, (b) find the range of possible values of k. 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_____________________________________________________________________________________ _____________________________________________________________________________________ Turn over 31   Question 12 continued _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ 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_____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ (Total for Question 12 is 6 marks)