A = [3, 4]
B = [1, 2]

A_plus_B = [A[0] + B[0], A[1] + B[1]]
print("A + B =", A_plus_B)

two_A = [2 * A[0], 2 * A[1]]
print("2 × A =", two_A)

norm_A = (A[0]**2 + A[1]**2)**0.5
print("A的模 =", norm_A)