The Muller method is a root-finding algorithm that estimates the root of a function by fitting a parabola through three points on the graph of the function. It works by first calculating the coefficients of a parabola that passes through three given points (x0, f(x0)), (x1, f(x1)), (x2, f(x2)). Then, the x-value where this parabola intersects the x-axis gives an estimated root. This process is repeated iteratively to converge on an accurate root. The document provides mathematical definitions of the Muller method and an example application with coefficients h = 0.1, x2 = 5, and x1 = 5.