# How do you factor by grouping mr + ns - nr - ms?

Mar 15, 2018

I tried this:

#### Explanation:

Collect $r$ from the first and third term and $- s$ from the second and fourth:

$m r + n s - n r - m s = r \left(m - n\right) - s \left(m - n\right) =$

now collect $m - n$:

$= \left(m - n\right) \left(r - s\right)$