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#2 2005-09-16 14:47:39
- hey
- Guest
Re: Factoring (X^2 - 4)
Back in High School in my Pre Cal class, I was shown how to factor something like
(X^2 + 4)
Now I can't think of a way how to factor it.
#3 2005-09-17 00:11:51
- nu
- Guest
Re: Factoring (X^2 - 4)
if you want to factor x^2-4 is easy: (x^2 - y^2) = (x + y)*(x - y), in your case (x+2)*(x-2)
if you want to factor x^2+4 you have to use Ruffini, or interpret this as (x^2 - y^2). The y in this case would be √-4=j√4:
(x^2-(√-4)^2) = (x + √-4 )*(x - √-4 ) = (x + j√4)*(x - j√4), j indicates it is an imaginary number (j = √-1).
nu
#4 2005-09-17 04:36:13
- mikau
- Super Member
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Re: Factoring (X^2 - 4)
Yeah, always remember the differance of two squares. x2 - y2 = (x + y)(x - y). Always be on the look out for numbers with integer square roots. For instance x2 - 25 = x2 - 52 = (x+ 5)(x-5). Also variables with even exponants other (then zero) can always be converted to a square. x4 = (x2)2
A logarithm is just a misspelled algorithm.
#6 2005-09-17 08:59:26
- MathsIsFun
- Administrator
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Re: Factoring (X^2 - 4)
LOL, maybe I should put that on my to-do list.
If you don't mind I will experiment with your post using the "math" tag:
mikau wrote:
Yeah, always remember the differance of two squares.
.
Always be on the look out for numbers with integer square roots. For instance .
Also variables with even exponants other (then zero) can always be converted to a square.
Example of the first one:
Code:
[math]\Large x^2 - y^2 = (x + y)(x - y)[/math]
Now, using the math tag makes things a *little* slower, so best to use when other options fail. I often just cut and paste the symbols from the top of the forum, but there is no "^4", so that is where the math tag could help.
"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman