diary on
s=tf('s')
 
Transfer function:
s
 
P=40/(s^2+15*s+50)
 
Transfer function:
      40
---------------
s^2 + 15 s + 50
 
H=(K)/(1+K*P)
 
Transfer function:
100 s^2 + 1500 s + 5000
-----------------------
   s^2 + 15 s + 4050
 
step(100*H)
diary off
s=tf('s')
 
Transfer function:
s
 
P=40/(s^2+15*s+50)
 
Transfer function:
      40
---------------
s^2 + 15 s + 50
 
K=61.25

K =

   61.2500

H=(K)/(1+K*P)
 
Transfer function:
61.25 s^2 + 918.8 s + 3062
--------------------------
    s^2 + 15 s + 2500
 
step(100*H)
diary off