Let f(x) = 5x^3 +4x + 8(adsbygoogle = window.adsbygoogle || []).push({});

(i) find f'(x)

answer--> 15x^2 + 4

(ii) Show that f(x) is increasing on ([tex]-\infty,\infty[/tex])

answer--> dont know how to prove it..

(iii)Hence find the minimum and maximum value of f(x) on the closed

interval [1,3]

answer-->please guide me to start aswering this question..

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