# Week 8 : Doubt in additional exercise

Below was the problem statement

In the solution for Z value it is mentioned as

``````matrix1 = np.random.rand(10,20)

matrix2 = np.random.rand(20,30)
z = np.dot(matrix1 , matrix2 )
``````

here the sigma n is not considered which is summation of all the values from 1 to n. Is it because n is not esed in the product .

It is because `np.dot()` is a generalized method, which works on matrices.
The formula snapshot that you’re sharing is based on elements of these matrices.