解聯立方程式（二）

 
import matplotlib.pyplot as plt
from sympy import Symbol,solve
import numpy as np
x=Symbol("x")
y=Symbol("y")
eq1=x+y-20
eq2=2*x+4*y-56
ans=solve((eq1,eq2))
print(ans)
print("雞有{}隻".format(ans[x]))
x1=np.linspace(0,31,100)
y1=-x1+20
#print(y1)
y2=(-2*x1+56)/4
plt.plot(x1,y1)
plt.plot(x1,y2)
plt.plot(ans[x],ans[y],"-o")
plt.text(ans[x],ans[y]+2,"("+str(ans[x])+","+str(ans[y])+")")
plt.show()