... f(x1),f(x 3 ),f(x2), butto the values f(x1),f(x 3 )eQ,f(x2)e2Q, yielding a new guess for the root, x4.Theoverall updating formula (incorporating the solution 9.2 .3) isx4= x 3 +(x 3 −x1)sign[f(x1) ... givesf(x1)− 2f(x 3 )eQ+ f(x2)e2Q=0 (9.2.2)This is a quadratic equation in eQ, which can be solved to giveeQ=f(x 3 )+sign[f(x2)]f(x 3 )2− f(x1)f(x2)f(x2)(9.2 .3) Now the false ... website http://www.nr.com or call 1-800-872-74 23 (North America only),or send email to trade@cup.cam.ac.uk (outside North America).2f(x) 134 xFigure 9.2 .3. Example where both the secant and false...