State, with explanation, whether the following statements are True or False:
a) It is possible for ? = ?(?) to have an inflection point at (?, ?(?)) even if ?′(?) is not defined.
b) If ?''(?) > 0 then ? has a local minimum at ? = ?.
c) For all functions ?, if ?′(?) exists ∀?, then ?′′(?) exists ∀?.
(a)
Inflection point can not be defined only if original function is not defined for that x-values
f'(a) or f''(a) may or may not be defined but f(a) must be defined
so, this is TRUE
(b)
f''(c) >0 means concave up
concave up means curve open upward
and function will be opened upward only after local minima
so, this is TRUE
(c)
f''(x) is derivative of f'(x)
derivative only exist when function is continuous
and function is continuous only when function is defined
so, to exist f''(x) , f'(x) must be continuous and differentiable
If f'(x) is continuous but not differentiable then f''(x) does not exist at that point
Hence,
this is FALSE
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