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

A_plus_B = [a + b for a, b in zip(A, B)]
print("A + B 的结果：", A_plus_B)

A_scaled = [2 * a for a in A]
print("2 × A 的结果：", A_scaled)

A_norm = math.sqrt(sum(a**2 for a in A))
print("A 的长度（模）：", A_norm)