Question 6255
Factor: ar^2 - brs + ars - br^2  

First, group the terms containing r^2 together and group the terms containing rs together.

(ar^2 - br^2) + (ars - brs)  From the first group, factor the r^2 and from the second group, factor the rs.

r^2(a - b) + rs(a - b)  Now factor the (a - b)
(a - b)(r^2 + rs) Finally, you can factor the r from the second group.

r(a - b)(r + s) and this is exactly equivalent to: r(r + s)(a - b)