ext_83795 (
randomchris.livejournal.com
) wrote
in
averygoodun42
2013-07-10 10:07 am (UTC)
no subject
For that one, think of (x+y) as being one number, call it z for now, because it's the same term in both equations.
So why is (2 + z) a factor of (4 - z^2)?
Because (2 + z) ( 2 - z) = 4 + 2z - 2z + z^2
The 2z terms cancel out, giving 4 - z^2.
It works when you put in numbers: if we have z = 10, then 4 - z^2 = -96, and 2 + z = 12. And 12 is a factor of -96. But algebra helps prove that it's true no matter what z you start with.
Does that help at all?
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no subject
So why is (2 + z) a factor of (4 - z^2)?
Because (2 + z) ( 2 - z) = 4 + 2z - 2z + z^2
The 2z terms cancel out, giving 4 - z^2.
It works when you put in numbers: if we have z = 10, then 4 - z^2 = -96, and 2 + z = 12. And 12 is a factor of -96. But algebra helps prove that it's true no matter what z you start with.
Does that help at all?