Step 1: Factoring numbers

First off, what is a factor?

"Natural number factors" are the complete set of whole numbers, where if you multiply one number in the set by another in the set, you get the number that you're factoring.

For example, the number 5 has two factors: 1, and 5. The number 6 has four factors: 1, 2, 3, and 6.

"Integer factors" include negative numbers.

The number 5 in this case would have four factors: -5, -1, 1, and 5. 6 would have eight factors: -6, -3, -2, -1, 1, 2, 3, and 6.

(Natural numbers are numbers without fractions, starting from 1, 2, 3, 4, 5... all the way up to infinity. Integers are natural numbers, as well as their negative counterparts and 0, or ...-5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5...)

Factoring numbers with the natural number set is simple. Every number has at least two factors. To find other factors, start dividing the number starting from two and working your way up until you reach that number divided by 2. Any quotient that does not have a remainder means that both the divisor and the quotient are factors of that number.

Say you need to factor the number 9. You can't divide by two evenly, so we skip it. (Note the solution, 4.5, so you know when to stop later on.) 9 is divisible by 3, so add 3 to your list of factors. Work your way up until you divide by 5 (9 divided by 2, rounded up). You'll end up with 1, 3, and 9 as a list of factors.

When factoring numbers in the integer set, you can just add the negative equivalent of your solutions from natural number factoring in. So 9 would have factors of -9, -3, -1, 1, 3, and 9.

Factoring negative numbers can only be done with integer factoring. The solution is the same one you get factoring the positive version of the number. -9 has factors of -9, -3, -1, 1, 3, and 9.

Zero is the only integer that has an infinite amount of factors, and is the only one that has zero as a factor.
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urg says: Nov 29, 2012. 12:32 AM
i really dont get it !
i want to learn more about it
sandyr1950 says: May 31, 2012. 11:22 PM
These things that are being factored are not EQUATIONS as stated in the text because they do not contain equal signs. They are called EXPRESSIONS. This is important because different things can be done with equations (such as solving) than can be done with expressions.
Phoenixsong (author) says: Jun 1, 2012. 8:54 AM
Will fix, thanks.
!!!Jenna!!! says: Mar 7, 2012. 8:44 PM
I don't understand how to simplify radical expressions. The whole Factor, Seperate, Simplify thing confuses me. I get most of it except how they factor and where they get all the random numbers from. I guess I just don't understand how to factor. For example, one of the questions was :...........

3(cube root) and then the radical sign and then 24n^2 x 3(cube root) and then the radical sign and then 36n^2..............

sorry i don't know how to make it look like the actual problem! How would I factor and solve that? Because obviously i am too dumb to figure it out on my own. online school is hard for me.
Phoenixsong (author) says: Mar 7, 2012. 10:17 PM
Also, as your question isn't directly related to the instructable, you'd be better off asking it on Yahoo Answers or similar.
Phoenixsong (author) says: Mar 7, 2012. 10:12 PM
By "and then" did you mean the two terms were set equal to each other? If so, cube both sides so you're left with:
24n^2 = 36n^2
And then move the 24n^2 to the other side of the equation:
36n^2 - 24n^2
Factor out the n^2:
n^2(36 - 24) = 0
Solve.
n = 0

If you meant that the two terms were added together, that's unfactorable.
bseibert says: Jan 2, 2012. 3:06 PM
Kumon's Math Study Guide provides this question:

Know how to "factor" Binomials:
Problem: -3x^2 + 7x
Answer: 0, 7/3

I thought the obvious answer is pulling out the x for the original binominal which would result in x (-3x+7)

Although I haven't seen this before, I could take each of the factors and have them equal 0 to come up with the answer. Am I missing something?

Example: x = 0 and -3x + 7 = 0
Solve for x, x = 0 and x = 7/3
Phoenixsong (author) says: Jan 2, 2012. 5:27 PM
You are exactly right. The problem should have been worded differently (something like 'Given -3x^2 + 7x = 0, solve for x.').
popewill says: Dec 4, 2011. 4:16 PM
Oh no. I hate factoring and FOILing with a passion. I thought it was the weekend but i guess you can never escape math :/.
mogg says: Jan 14, 2011. 7:39 PM
(2x^2 +5x^7) (1+3x) ->
x^2(2+5x^5)(1+3x)

Answer has 3 factors (^^)
Phoenixsong (author) says: Jan 14, 2011. 8:14 PM
Nice catch!
neomancer45 says: Jan 6, 2011. 2:24 PM
This instructable and all possible future ones would be easier to read if you used the conventional sign indicating a power, the carrot. (^)

2x2 is strange looking, and could b thought of as 2 times x times 2

also, this gets more complicated when u have variable powers, as x to the power of y, which is different when written as xy.

ex:
x to the power of 4
wrong:
x4
right:
x^4
Phoenixsong (author) says: Jan 6, 2011. 3:13 PM
When this article was written, instructables turned anything between two carets into superscript. It looks like that functionality is not working properly at the moment; although it looks fine in the editor, the formatting does not apply in the published version.
Phoenixsong (author) says: Jan 6, 2011. 3:24 PM
As this has been an issue for a while, I'm assuming instructables has gotten rid of the superscript feature, and I'll insert carets where necessary. Thanks for reminding me.
ilovetine says: Sep 27, 2010. 5:10 AM
can you please give an example of factoring binomials ?
Mattonator says: Sep 4, 2009. 6:46 PM
In the binomials section he tries to explain how to factorise 2x2-4x, to get to the answer 2x(x-2). He did this by expanding the binomial function. The common factor in the equation 2x2-4x is 2x, this is because there is a 2x in 2x2 obviously but a 2x inside -4x also. therefore if you times 2x(x-2) out you will get 2x2-4x. This is because 2x times x = 2x2 which is the first part of the equation and 2x times -2 gives the answer -4x because a positive times a negative is a negative number.

Hope this explains it, if not, reply to me
Saltyseaman says: Jan 13, 2010. 11:23 AM
factor, not factorise. you just failed at trying to look smart.
ladams234 says: Sep 13, 2009. 9:08 AM
Need more explanation, please. For example, how would you factor 4v squared - 81t squared. I cannot figure it out from the instructable above, or yours. HELP!
Phoenixsong (author) says: Sep 13, 2009. 11:50 AM
4v2 - 81t2

Square root both of the terms in the function. You'll end up with 2v and 9t.

Then, plug it in to the set pattern, (x + y)(x - y).

(2v + 9t)(2v - 9t)
ladams234 says: Sep 13, 2009. 2:24 PM
Thanks! I did some research and found the same answer you did. I just wasn't quite understanding it before - thanks again!
Mister nobodie says: Sep 3, 2009. 12:37 PM
Rated 0.5 (worthless). And thats really what this is. You didn't even explain how you got to 2x (x - 2) for the binomials section. This is pretty much what you did: HOW TO FACTOR 1) factor problem 2) get answer.
Saltyseaman says: Jan 13, 2010. 11:23 AM
Nerd rage.
bassclarinet23 says: Dec 2, 2009. 1:19 PM
My teacher gave us a song to memorize the Quadratic Equation...

(Imagine the tune of "Pop! Goes the Weasel".)

The opposite of lower case "B",
Plus or minus the square root,
Of "B" squared minus 4(ac),
All over 2a.

Fin.

It's irritating, but you'll remember the formula.


Pronounce...
4(ac) = four "A" "C"
2a = two "A"

Phoenixsong (author) says: Dec 2, 2009. 4:01 PM
I was taught it to the tune of Row, Row, Row your boat:

x equals minus b,
plus or minus root,
b squared minus four a c,
all over two a.

:)
bassclarinet23 says: Dec 2, 2009. 5:27 PM
Ha ha. Cool.
mi9d says: Nov 8, 2008. 5:34 AM
Sorry, but shouldn't n=3.x.x ?
I mean 9.x.x times 9.x.x = 81.x.x.x.x

( sorry, can't type the power superscripts )
Mattonator says: Sep 4, 2009. 6:55 PM
9x2 times 9x2 is 81 * 81 which = 6561 which is the same as 9*9*9*9 or 94.

814 is 43,046,721
Phoenixsong (author) says: Nov 8, 2008. 7:44 PM
Oh, and btw, to type power superscripts, put a carrot (shift+6) both in front of and in back of the number/word/phrase that you want in superscripts.
Phoenixsong (author) says: Nov 8, 2008. 7:38 PM
Gotcha. Thanks for catching that.
Shinta786 says: May 8, 2009. 11:56 AM
oh man, I just scrolled to the comments in 5secs. don't dare to read this, but must be good
mad rabid sh33p says: Oct 27, 2008. 3:56 PM
I hate factoring lol - we have to do this huge 125 Q. packet for Algebra II. If I need help, I'll be sure to reference this. ;D
Blazo says: Oct 12, 2008. 1:27 AM
This is a good instructable and i dont know about you but we learned this in 7th grade. By the way im from Macedonia and at 7th grade kids are usualy 12-13 yrs old. :D
menace says: Oct 3, 2008. 9:56 PM
How about factoring polynomials?
ax4+bx3+cx2+dx+e
synthetic division
normal division those would be reallly helpful.
Phoenixsong (author) says: Oct 4, 2008. 11:49 AM
If you wanted to use long division instead of synthetic division, you could divide the polynomial through by x - P/Q. (If that's what you mean...) Synthetic division goes by quicker, though.
josefu0 says: Sep 28, 2008. 8:41 PM
omg this schooling is boring.
Phoenixsong (author) says: Sep 28, 2008. 11:56 PM
No one said you had to read it. >_>
Heyarnold says: Sep 26, 2008. 6:19 AM
FOIL ftw! brings back memories of my math tutoring days.
codz30 says: Sep 22, 2008. 11:45 PM
HP 39gs -> POLYROOT
Phoenixsong (author) says: Sep 23, 2008. 9:10 PM
Added section on factoring programs. Thanks.
undeadbydawn says: Sep 23, 2008. 12:18 PM
this is a really nice, deep and informed feature... except in that you use the word 'factor' four times in explaining what a factor is. So unless you already know what a factor is the explanation isn't going to make sense. 1st rule of explanation: assume your student knows nothing. Otherwise, math tutorials are a Damned Fine Plan, please do keep 'em coming :-)
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