Quick math help

[Dillinger4]

Im usually pretty good at these types of problems but this one seems to puzzle me. x(x-y)-y(y-x)-(x²-y²)
What i end up getting boils down to -xy + yx Thanks

[sql_lall]

multiplication of numbers works either way (there is a word for this, i just can't remember it right now)
=> -xy + yx
= xy-xy = 0 (which i hope is the required answer)

However, if x and y are matrices, i'm not sure how this would be done.

To check:
x(x-y)-y(y-x) = x(x-y)+y(x-y) = (x+y)(x-y) = x²-y²

x²-y² - (x²-y²) = 0

[Dillinger4]

Humm very interesting. I kinda thought that zero might be the solution but i wasn't too sure. I guess if values are substituted then the answer becomes apparent. -1(3) + 3(1) = 0 Thanks for the help.