The question is:
Let A= [2 5, -3 1] and B=[4 -5, 3 k]
I don't know if this will represent A and B better:
[2 , 5] [4 , -5]
[-3 , 1] [3 , k]
What value(s) of k, if any, will make AB=BA?
I got no values of k, but the back of my book claims the answer is (k-5). Can anyone tell me if I am right or wrong?
Fine, but a piece of advise: do not do mathematics with your computer! Grab a pencil (or a pen), a sheet of paper (or better: 37436 sheets of paper) and begin to write. Much better if you can get chalk and a blackboard.
After you do maths this way, then you can go to the puter and write it down nicely.