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L3
07-22-2009, 06:52 AM
I'm very confused by factoring. I just can't remember how to do it, and I can't find any site online that will help me. In the math lesson I'm reading at the moment it factors x[sup:360hykfh]3[/sup:360hykfh] - 4 * x into (x + 2) * x * (x - 2). And Ijust don't see how it gets there and I've looked for math sites that would explain it to me and still just don't get it. I can see that, x[sup:360hykfh]3[/sup:360hykfh] - 4x you could factor x and get
(x[sup:360hykfh]2[/sup:360hykfh] - 4) * x but I don't understand how you get (x + 2) and (x - 2).

I mean I would think that x + 2 * x - 2 would get you x[sup:360hykfh]2[/sup:360hykfh] - 4 (though my calculator for some reason when I type that in, gives me -3 * x which doesn't really make sense to me, and I expect that answer might be due to the way I'm writing the question, I've never really figured out this calulator. And when I I try it on paper, using FOIL on (x + 2 )* (x - 2) I do get x[sup:360hykfh]2[/sup:360hykfh] - 4.) So I can see how you get from (x + 2 )* (x - 2) to x[sup:360hykfh]2[/sup:360hykfh] - 4 but not the other way around.

I really have tried to find an explanation online, and I know it's clearly that I just don't understand factoring, but I don't know where I'm going wrong, or what to look for.

Aladdin
07-22-2009, 08:49 AM
I'm very confused by factoring. I just can't remember how to do it, and I can't find any site online that will help me. In the math lesson I'm reading at the moment it factors x[sup:2gaac9jn]3[/sup:2gaac9jn] - 4 * x into (x + 2) * x * (x - 2). And Ijust don't see how it gets there and I've looked for math sites that would explain it to me and still just don't get it. I can see that, x[sup:2gaac9jn]3[/sup:2gaac9jn] - 4x you could factor x and get
(x[sup:2gaac9jn]2[/sup:2gaac9jn] - 4) * x but I don't understand how you get (x + 2) and (x - 2).
Factorise: a^2 - b^2 = (a-b)(a+b)-- here you have x^2 - 2^2 which fits in (x-2)(x+2)

I mean I would think that x + 2 * x - 2 would get you x[sup:2gaac9jn]2[/sup:2gaac9jn] - 4 (though my calculator for some reason when I type that in, gives me -3 * x which doesn't really make sense to me, and I expect that answer might be due to the way I'm writing the question, I've never really figured out this calulator. And when I I try it on paper, using FOIL on (x + 2 )* (x - 2) I do get x[sup:2gaac9jn]2[/sup:2gaac9jn] - 4.) So I can see how you get from (x + 2 )* (x - 2) to x[sup:2gaac9jn]2[/sup:2gaac9jn] - 4 but not the other way around.

I really have tried to find an explanation online, and I know it's clearly that I just don't understand factoring, but I don't know where I'm going wrong, or what to look for.

masters
07-22-2009, 01:49 PM
I'm very confused by factoring. I just can't remember how to do it, and I can't find any site online that will help me.

I really have tried to find an explanation online, and I know it's clearly that I just don't understand factoring, but I don't know where I'm going wrong, or what to look for.

Hi L3,

I understand your frustration. It just takes a lot of practice to understand factoring and to be able to do it quickly and with confidence.

I don't know why you can't seem to find references to "factoring polynomials" using google. There's a bunch out there.

Start here: http://www.purplemath.com/modules/simpfact.htm

with a site that was created by one of the mods on this forum. Study over the 2 pages of explanations and then go here: http://www.purplemath.com/modules/simpfact.htm

If that's not enough, just google "factoring polynomials" and take your pick.

Good luck, and happy factoring.

L3
07-23-2009, 06:01 AM
Thank-you very very much :-)