f(2.5)=( 1/k)f(2.5-2)=( 1/k)f(0.5)=( 1/k)* 0.5 *(0.5-2)=-3/(4k)

(2)

1) If-4

f(x)=kf(x+2)=k^2f(x+4)=k^2(x+4)(x+2)

2) if-2 < = x <; =0, then 0

f(x)=kf(x+2)=kx(x+2)

3) If 2

f(x)=( 1/k)f(x-2)=( 1/k)(x-2)(x-4)

Therefore, the expression of f(x) is:

f(x)={k^2(x+4)(x+2)(-3<； = x & lt=-2)、kx(x+2)(-2 & lt； = x & lt=0)、x(x-2)(0 & lt； = x & lt=2)、( 1/k)(x-2)(x-4)(2 & lt； = x & lt=3)

F(x) increases at (-3,-1), decreases at (-1, 1) and increases at (1, 3).

It is not easy to answer this question. Please accept it if you are satisfied ~ thank you.