How do you do matrix multiplication?

2 4 times -1 3
1 1 5 2

Question

How do you do matrix multiplication?

2 4  times  -1 3
1 1              5 2

jim_thompson5910 · Answer

The first row of the left matrix is  2   4

The first column of the right matrix is  -1  5

jim_thompson5910 · Answer

Multiply the corresponding values and add them up:

2*(-1) + 4*5 = -2 + 20 = 18

jim_thompson5910 · Answer

So the element in the first row and the first column of the new 2x2 result matrix is 18

anonymous · Answer

so to get the 2 term in the first row it would be... row 1 times column 2 and add them like you did above. And repeat for row 2?

jim_thompson5910 · Answer

yes in a way that's what you're doing 

to find the element in row 1, column 2 of the answer, you "multiply" row 1 of matrix 1 by column 2 of matrix 2 and add up the products

anonymous · Answer

18 14
4   5

jim_thompson5910 · Answer

2*3 + 4*2 = 6 + 8 = 14

so 14 is in row 1, column 2 of the answer

anonymous · Answer

Thanks, I was forgetting the adding step.

jim_thompson5910 · Answer

you have the correct answer