Answer :

Solution :

Given:

Forward path gain = G

Feedback path gain = H

Input signal = R(s)

Output signal = C(s)

Error signal = E(s) C(s) = G × E(s)

Error signal = Input signal - Feedback signal

E(s) = R(s) - H × C(s)

E(s) = R(s) - H × G × E(s)

E(s) + H × G × E(s) = R(s)

E(s) [1 + GH] = R(s)

$\frac{E(s)}{R(s)}={\displaystyle \frac{1}{(1+GH)}}$