If S1 ands2 are respectively the sets of local minimum and local maximum points of the function fX9x
Function f(x) = 9x is a linear function and continuously increasing function. This function does not have any minimum or maximum until unless the domain is not specified. For example if domain is [a, b] for some a and b then local maximum over this interval is b and local minimum over this interval is a.
So, the given function does not have any minimum or maximum unless the domain is specified.
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