Show that the derivative of the function f given by f (x) = 2x3 – 9x2 + 12x + 9, at x = 1 and x = 2 are equal.

We are given with a polynomial function f(x) = 2x3 - 9x2 + 12x + 9, and we have to find f ‘(x) at x = 1 and x = 2, so by using the formula, f ‘(c) = , we get,

f ‘(1) =


f ‘(1) =


f ‘(1) =


f ‘(1) =


f ‘(1) = limx1 2x2 - 7x + 5 = 0


for x = 2, we get,


f ‘(2) =


f ‘(2) =


f ‘(2) =


f ‘(2) =


f ‘(2) = limx2 2x2 - 5x + 2 = 0


Hence they are equal at x = 1 and x = 2 .


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