How do you factor by grouping: #r^2 - 20tw + 4wr - 5tr#?

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Answer 1 · 2015-04-09T23:03:26

#r^2-20tw+4wr-5tr#

Group #r^2# and #-5tr#, and #4wr-20tw#.

#r^2-5tr+4wr-20tw#

Factor out the #r# from the first group, #r^2-5tr#.

#r(r-5t)+4wr-20tw#

Factor out #4w# from the second group, #4wr-20tw#.

#r(r-5t)+4w(r-5t)#

Factor out the common term.

#(r+4w)(r-5t)#