Find the ultimate gain and frequency for a proportional controller in the case of a process having the transfer function Gp(s) = 1/(4s + 1)(2s + 1)(s + 1).

• w = 1/14, Kc = 45/714
• w = 7/6, Kc = 46/3
• w = 1, Kc = 13
• w = 7/8, Kc = 45/4