In an autocatalytic chemical reaction, the product formed acts as a catalyst for the reaction. If $Q$ is the amount of the original substrate present initially and $x$ is the amount of catalyst formed, then the rate of change of the chemical reaction with respect to the amount of catalyst present in the reaction is
$$
R(x)=k x(Q-x) \quad(0 \leq x \leq Q)
$$
where $k$ is a constant. Show that the rate of the chemical reaction is greatest at the point when exactly half of the original substrate has been transformed.