import numpy as npimport matplotlib.pyplot as pltx=np.arange(-3,3,0.1)y=3*(x**3)+2*(x**2)#一阶导数y1=9*(x**2)+4*x#二阶导数y2=18*x+4 plt.plot(x,y,label="y")plt.plot(x,y1,label="y'",linestyle="--")plt.plot(x,y2,label="y''",linestyle="-.")plt.xlabel("x")plt.ylabel("y")plt.title("y&y'&y''")plt.legend()plt.show()