Consider the quadratic polynomial $f(x) = x^2 − 6x + 2$. The two roots of this function are $R_1 = 3 + \sqrt 7$, $R_2 = 3 − \sqrt 7$. Consider the following 4 different iterative processes.
a)$X_{n+1}=6-\frac{2}{X_n}$;
b)$X_{n+1}=\frac{1}{6}X_n^2+\frac{1}{3}$;
c)$X_{n+1}=\sqrt{6X_n-2}$;
d)$X_{n+1}=\frac{X_n^2-2} {2X_n-6}$;