SOLUTION: I am confused on "Factor by Grouping". The problem I am working on is this : mn + 5n^2 - 4m - 20n Any help provided with the answer so I can have a correct example to go through t

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: I am confused on "Factor by Grouping". The problem I am working on is this : mn + 5n^2 - 4m - 20n Any help provided with the answer so I can have a correct example to go through t      Log On


   

Question 908426: I am confused on "Factor by Grouping". The problem I am working on is this :
mn + 5n^2 - 4m - 20n Any help provided with the answer so I can have a correct example to go through the rest of my homework with would be outstanding, thank you !
Found 2 solutions by josmiceli, richwmiller:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
+mn+%2B+5n%5E2++-+4m+-+20n+
change the grouping:
+%28+5n%5E2+-+20n+%29+%2B+%28+mn+-+4m+%29+
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Factor +5n+ out of the 1st group
+5n%2A%28+n+-+4+%29+%2B+%28+mn+-+4m+%29+
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Factor +m+ out of the 2nd group:
+5n%2A%28+n+-+4+%29+%2B+m%2A%28+n+-+4+%29+
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Now +n+-+4+ can be factored out
the 1st and 2nd terms
+%28+n+-+4+%29%2A%28+5n+%2B+m+%29+
This is as far as I can go with it

Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
It helps if you can see the relationship between 4, 5 and 20
mn - 4m+5n^2 -20n
m*(n-4)+5n*(n-4)
(m+5n)*(n-4)