**?? - 2015 q9**

9. Given that

*k*is a negative constant and that the function f(*x*) is defined by(a) show that

(b) Hence find f '(

(c) State, with a reason, whether f(

*x*) , giving your answer in its simplest form. (3)(c) State, with a reason, whether f(

*x*) is an increasing or a decreasing function. Justify your answer. (2)