This document discusses optimization methods in pharmaceutical product development. It introduces the simplex method, which uses geometric figures to optimize formulations based on multiple variables. For two variables, the simplex is a triangle, and for three variables it is a tetrahedron. The basic simplex method replaces the worst performing vertex with a new point, while the modified simplex method allows the shape and size of the simplex to vary. The modified method uses reflection, expansion, contraction exterior, and contraction interior operations to move away from worst responses and find the optimal formulation.