Python

import numpy as np

a = np.array([
    [1.75, 1.66, 1.84, 1.98],
    [100.00, 67.00, 87.32, 90.43],
])

bmi = np.array([a[1] * a[0] ** 2])

a = np.concatenate((a, bmi), axis=0)
print(a)
print(a[:, 1])