#How to find "i" import random PV = 3790.75 P = 1000. n = 10 a = random.random()+1. Tol = 0.001 No = 10000 def f(PV, P, n, x): f = x**(-n) + (PV/P)*x - (PV/P) - 1. return f def fp(PV, P, n, x): f = -n*x**(-n-1.) + (PV/P) return f i = 1 while i<=No: p = a - f(PV, P, n, a)/fp(PV, P, n, a) if abs(p-a)<Tol: print ('success') print (('i ='), round(p,2)-1.) break i = i+1 a = p if i>No: print ('unsuccess')