text: import numpy as np
  import matplotlib.pyplot as plt
  
  x = np.linspace(0, 10)
  plt.plot(x, np.sin(x), label=r"$\sin(x)$",
           linestyle='-', color='black')
  plt.plot(x, np.cos(2 * x), label=r"$\cos(2x)$",
           linestyle='--', color='blue')
  plt.xlabel(r"$x$")
  plt.ylabel(r"$f(x)$")
  plt.legend()
  