There is a special index -1, which represents the last element in an array. There are several ways to get more than one consecutive elements. x_np[1:3) gives the 2nd and 3rd elements only. It starts with the first index and ends before the second index. So the number of element is just the difference between these two numbers. x_np[1:-1) is the same as x_np[1:3] for a 4-vector. If you want the last element also, then you do not need to put the index, e.g., X_n[1:) gives all elements except the first one. You can do the same thing as the first one. | DO THIS: you are given a vector ( x_np ) of n elements, define a new vector (d) of size n - 1 such that di = Xit1 x; for i = 1, ...,n - 1. Hint try doing this without writing your own loop. You should be able to use simple numpy indexing as described above. [2]: x_np = np.array([1,8,3,2,1,9,7]) d = np.array([x_np[1:]-x_np[@: -1]]) print(d) ## Put your answer to the above question here. NameError Traceback (most recent call last) in ----> 1 x_np = np.array([1,8,3,2,1,9,7]) 2 d = np.array([x_np [1: ]-x_np[: -1]]) 3 print(d) 4 ## Put your answer to the above question here. NameError: name 'np' is not defined [4]: from answercheck import checkanswer checkanswer(d, '14205415f0ed56e608d0a87e7253fa70'); ModuleNotFoundError Traceback (most recent call last) in