#!/usr/bin/python3
import numpy as np
import math
import matplotlib.pyplot as plt
import mpl_toolkits.mplot3d as Axes3D


def polyx(a,x):
    f = 0
    for i in range(0,len(a)):
        f+=a[i]*x**i
    return f

x = np.linspace(-3,3)

plt.plot(x,polyx([1,-2,1],x))
plt.show()