from matplotlib.pyplot import plot, show, grid, subplots, axhline, axvline
from numpy import linspace

x = linspace(1, 3, 100)
y = -0.2*x**3 + 0.1*x**2- 0.3*x + 2
z = 0.3*x**3 - 0.5*x - 1

fig, ax = subplots(figsize=(2, 1))
ax.set_ylim(0,1)
plot(x,y)
plot(x,z)
grid(linestyle='--')

axhline(y=0, color='black', linestyle='-')
axvline(x=0, color='black', linestyle='-')

show()