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    I have a function which is in the form of

    f(x)=(1-k^x)/x

    with the restraints 0<k<1 and x > 0. The questions asks me to prove that the derivative is less than 0 (i.e. negative slope) for all x > 0

    They've given me a hint which is to use the proof ln(x) is less than or equal to (x-1) for all cases of x. I've done it using an alternative method but can't do it through the hint. Any help would be appreciated!!!:confused:
 
 
 
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