1.import numpy as npnum_arr = np.arange(1, 21)print(num_arr)print(num_arr[::-1])print("num_arr 내의 모든 원소의 합 :",np.sum(num_arr))print(num_arr.reshape(5, 4)) 2.import numpy as npn_arr = np.arange(25)n_arr = n_arr.reshape(5, 5)print(n_arr)print("첫 원소 :", n_arr[0, 0])print("마지막 원소: ", n_arr[-1, -1])print(n_arr[:2])print(n_arr[2:5])print(n_arr[:,::2])print(n_arr[::2, ::2])print(n_arr[0:2].reshape(5, 2..