Question

Find DE if D=[-2 4 6] and E=[1 -2]
[5 -7 1] [0 4]
[-3 4]

I followed the example in the book on how to multiply matrices and one I found on the Internet and keep coming up with the same answer which is not one of the solutions given to choose from.

WORK: [(-2)(1)+(4)(0)+(6)(-3)]=-20
[(-2)(-2)+(4)(4)+(6)(4)]=44
[(5)(1)+(-7)(0)+(1)(-3)]=2
[(5)(-2)+(-7)(4)+(1)(4)]=-34

I keep getting [-20 44]
[2 -34]

Answers to choose from are:

A) [20 44] B) [-20 8]
[8 42] [44 42]

I don't know where I am going wrong, so hopefully this will stay aligned and you can see where I am making my mistake!!

Thanks.

Answer 1

did not stay aligned so I will try something else.

Answer 2

I understand what you did and agree with your answer
-20__44
__2_-34