 In this video, we present the solution to question number one from practice exam two from math 2270 We are asked to multiply together a 2 by 3 matrix and a 3 by 5 matrix and determine the shape of their product a times b Now a matrix products are only defined When the number of columns of the first factor is equal to the number of rows in the second factor We see that right here. So this is a defined product because we have three and three We are going to basically just remove these from consideration And so the resulting shape should be 2 by 5 which then gives us answer D