Expert: Lynn Houston - 7/20/2011

Question
how can i factor mr + ns - nr - ms

Answer
yes, swap the ns and -nr so you have

mr - nr + ns -ms, then factor out the r and s.

r(m-n) + s(n-m)

You could also swap ms and ns and factor out the m and n

m(r-s) + n(s-r)  then, multiply either of the second elements by -1 and you can factor further
m(r-s) - n(r-s)
(m-n)(r-s)