Question 107867
You are right; there are options at times but
not arbitraries.
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Your problem:
original problem to be factored by grouping: 
p^2-2p-3rp+6r
original problem to be factored by grouping: 
p^2-2p-3rp+6r
p(p-2) -3r(p-2)
(p-2)(p-3r)
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Cheers,
Stan