prison method, applications to modelling In this test, trigonometric functions use radians. 1. Let f(x) = 20x3+5x2 -4. a) Show that f(x) = 0 can be rearranged into the form x = 0.2-0.25x?. [1] The equation f(x) = 0 has a solution a in the interval [0.5, 0.6]. b) Use the iterative formula x.., = /0.2-0.25x, with x. =0.6 to find, to 3 decimal places: i) x , ii) * 2 iii) x , iv) X4 [8] c) By considering a suitable interval, show that a = 0.3122 to 4 decimal places. 131