Вариант 17 / 2 / 2

import math
x = [0.95, 1, 1.05, 1.1]
y = [-0.6565, -0.2, 0.294, 0.827]

def lx(k, x, y, xl):
    l = 0
    for i in range(0, k):
        l1 = 1
        for j in range(0, k):
            if i != j:
                l1 = (x[0]- x[j])/(x[i] - x[j]) * l1
        l += l1
    return l

def lag(x, y, xl, n, e):
    k = 0
    L = []
    B = lx(k, x, y, xl)
    A = B
    B = lx(k, x, y, xl)
    L[k] = B
    e1 = abs(B - A)
    while e1 >= e or k <= n:
        A = B
        k += 1
        B = lx(k, x, y, xl)
        L[k] = B
        e1 = abs(B - A)
    return L

print(lag(x, y, 1.02, 2, 1e-4))