To describe the effect of a drug it is necessary to know both its concentration and how it influences

the body. The relation between concentration c and its effect e is typically nonlinear. A simple

model is

e $=$ emax$($c$/($E $+$ c$))$

where emax, E are constant values denoting the maximum effects and the concentration of the drug

that gives half $(50\%)$ maximal response, respectively. Linearize about the concentration c$0.$