import matplotlib.pyplot as pl
import numpy as np

k = int(input("k = "))
x = np.linspace(-3, 3, k)
y = (x + 2)/(x * x + 3)
y1 = 0.3 * x ** 2

pl.xlabel("x")
pl.ylabel("y")
pl.title("Графики функций")
pl.grid(True)
pl.plot(x, y, 'g-', 
        linewidth=2, 
        label='(x + 2)/(x * x + 3)')
pl.plot(x, y1, 'r--', 
        linewidth=2, 
        label='0.5 * x ** 2')
pl.legend(fontsize=10)
pl.show()