http://i24.tinypic.com/2hncsgh.jpg

I don't understand how to do this...

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- Oct 13th 2007, 02:31 PMfluffy_penguinFactor by grouping
http://i24.tinypic.com/2hncsgh.jpg

I don't understand how to do this... - Oct 13th 2007, 03:14 PMtopsquark
- Oct 13th 2007, 07:00 PMfluffy_penguinConfused
- Oct 13th 2007, 07:12 PMJhevon
we use \bold{ } to make something bold with LaTex

topsquark noticed that 9a - 7a = 2a. how did he do that? well, he could have done it by experience, but there is a method you can do.

take the coefficient of a^2, that is 3 and multiply it by the constant term, that is, -21. the result is -63. now you want two numbers that when multiplied give -63 but when added give 2 (which is the coefficient of the middle term). 9 and -7 are such numbers. now we split the middle term into those two numbers and continue as topsquark did - Oct 13th 2007, 07:20 PMfluffy_penguin
Okay thank you both of you. ^ ^

- Oct 13th 2007, 07:29 PMJhevon