Python - Matrices

import numpy as np
from numpy import matrix
a= matrix([[2,4,1],[1,-2,3],[5,0,-1]])
b= matrix([[3,-1,-2],[0,5,6],[0,0,9]])
c= matrix([[2,0,-1],[10,-1,2],[1,-2,5]])
r1=-a-b+c
r2=a+b-c
r3=3*a+c/2
print("\ta-b+c")
print(np.linalg.det(a))
print(a.shape)
print(a.dtype)
print (r1)
print()
print("\ta+b-c")
print(np.linalg.det(b))
print(b.shape)
print(b.dtype)
print (r2)
print()
print("\t3*a+c/2")
print(np.linalg.det(c))
print(c.shape)
print(c.dtype)
print (r3)