Engineering
Mathematics
Maxima and Minima
Question

Let f be a function defined on R (the set of all real numbers) such that

f '(x) = 2010(x - 2009)(x - 2010)2(x - 2011)3 (x - 2012)4, for all x ∈ R.

If g is a function defined on R with values in the interval (0, ∞) such that

 f(x) = ln (g (x)), for all x ∈ R,

then the number of points in R at which g has a local maximum is

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Solution

g (x) = ef (x)

g ' (cx) = ef (x) f ' (x)

f ' (x) = 2010 (x – 2009)(x – 2010)2(x – 2011)3(x – 2012)4

g ' (x) = 0                  x = 2009, 2010, 2011, 2012

for max.  g ' (x) must change sign from + ve to – ve 

x = 2009

     1

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