What does this question have to do with increase or decrease?
As we can see we have
s/(n+v) > s / ( n+v+z) because n,v,z > 0
Thus [ s/(n+v)]^ 1/(1-b) > [ s / ( n+v+z)] ^ 1/(1-b)
Also The value of k1 and k2 hereafter will depend on the value of A which may make k1 greater than, equal to or less than k2