Question 89001
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i have to factor 
{{{2x^2 + 18x - 90}}}
i used the a-c metod but there was nothing
in common for -180 and 18 so i used the gcf 
method and divided by 2 so i got {{{2(x^2 + 9x - 45)}}} 
and i still could not find anything in common 
for -45 and 9.

LOL. You just didn't know when to stop!

{{{2x^2 + 18x - 90}}}

factors just as you had it:

{{{2(x^2 + 9x - 45)}}}

It doesn't factor further, because as you said, there
are no two positive integers with product 45 and 
difference 9.  But you DID factor it, because taking 
out a common factor IS factoring.  You just thought 
it had to factor further. 

Incidentally, I noticed you tried the a-c method
first.  When you have a trinomial, don't try the 
a-c method first. Instead look for a common
factor first, and only when there isn't a common
factor should you try the a-c method.

Edwin</pre>