import numpy as np
import matplotlib.pyplot as plt

def f(x):
    return x**2 + 3

def g(x):
    return 3*x - 1

xa = np.linspace(-2, 3, 100)

plt.close('all')
plt.figure(1, figsize=(12, 9))

plt.plot(xa, f(xa), xa, g(xa))
plt.legend(labels=('f(x)','g(x)'))

plt.savefig('plot_fun_plot.pdf')
plt.show()