import matplotlib.pyplot as plt import numpy as np x=np.linspace(-3,3,50) y1=x*2+1 y2=x**2 plt.plot(x,y1) plt.figure(num=3,figsize=(8,5)) plt.plot(x,y2) plt.plot(x,y1,color="red",linewidth=1.0,linestyle="--") plt.show()