Plug in 1 / k for n:

 (1 – k) / (1- (1 / k))
 = (1 – k) / ( (k/k) – (1/k))
 = (1 – k) / ((k – 1) / k))
 = (1 – k) * ( (k) / (k – 1))
 = (k (1-k)) / (k – 1)
 = - (k (l – k) )/ (1 – k)
 = -k (B)
 

Back to Answer Sheet