Solution
= Solution
The removal rate is $\dot R=\gamma I$. Because $\gamma$ is constant, its interior peak occurs when $I$ is maximal. At such a point,
$$
0=\dot I=I(\beta S-\gamma),
$$
and $I>0$, so
$$
S=\frac\gamma\beta.
$$
= Solution
The removal rate is $\dot R=\gamma I$. Because $\gamma$ is constant, its interior peak occurs when $I$ is maximal. At such a point,
$$
0=\dot I=I(\beta S-\gamma),
$$
and $I>0$, so
$$
S=\frac\gamma\beta.
$$