The document describes Newton's method for finding the roots of a function. It works by using the tangent line at a given point as a linear approximation of the function. The x-intercept of this line is then used as the next estimate in the sequence. The process is repeated, using the new point's tangent line each time, with the estimates getting closer to a root as long as the linear approximations remain accurate. While faster than bisection, Newton's method can fail if the derivative approaches zero at a turning point, causing the linear model to become flat and send the estimates far off course.