1 (8 points) (8 points) Steffensen's method for solving the nonlinear equation ()=0 uses the following iteration formula +1=()(), where ()=(+())()(). If this method converges for an initial point 0 , show it usually has quadratic convergence rate. What is the advantage of this method over Newton's method? Hint: To establish the quadratic convergence, in addition to expand the Taylor series of () about , which was used in our convergence analysis of Newton's method, expand the Taylor series of (+()) about