Hi
What do i get when i expand:
x^2 - 1
Is it
(x-1)(x+1)
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Hi
What do i get when i expand:
x^2 - 1
Is it
(x-1)(x+1)
expand? there is nothing to expand here, you'd get just that. did you mean factorize? this is the difference of two squares,Quote:
Originally Posted by taurus
yes thanks
Just a quick question:
is it ok to write
21 - 4x - x^2
as
x^2 + 4x - 21?
not unless it is equated to something where you can distribute the minus on the other side as well:Quote:
Originally Posted by taurus
so, say you had: 21 - 4x - x^2 = 0
then it is okay to multiply both sides by -1 to get: x^2 + 4x - 21 = 0
but if you just have the expression by itself, you cannot do that, the best you can do is to say:
leave the minus outside of the brackets
so for example this:
1/(21-4x-x&2)
Which one do i use?
it is not equated to anything.Quote:
Originally Posted by taurus