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Mathematics 22 Online
OpenStudy (safia21):

Factor each completely. 7x^2- 31x-20 5p-p-18 Factor each completely. 7x^2- 31x-20 5p-p-18 @Mathematics

OpenStudy (saifoo.khan):

\[(x-5) (7 x+4) \]

OpenStudy (saifoo.khan):

what's the second thing?

OpenStudy (safia21):

how did you get the first one?

OpenStudy (saifoo.khan):

we want two terms to which after multiplication we get 140. and after addition we get -31.

OpenStudy (saifoo.khan):

so, 7x^2 - 31x - 20 those two terms are, -35 and + 4.

OpenStudy (safia21):

can you do it with the diamond?

OpenStudy (saifoo.khan):

umm, no! :o what's that?

OpenStudy (safia21):

nvrm

OpenStudy (anonymous):

take the first term 7 and multiply by the last 20 to give 140. Rewrite saying x^2-31x-140. Now factor. Rewrite the two factors containing 7 in front of x. now factor out each expression and throw away the factor. Works everytime.

OpenStudy (anonymous):

http://mathforum.org/library/drmath/view/56442.html

OpenStudy (anonymous):

That post will show you how.

OpenStudy (saifoo.khan):

http://www.youtube.com/watch?v=fPjmX2H39dw

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