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 mvho May 22nd, 2009 02:16 PM

Question: For x<0, simplify the following:
** Hint: $\sqrt{x^2}$

$\sqrt{x^4-4x^2}/x$

$-\sqrt{x^2-4}$

I know I can simplify further ( difference of sq. ) But this looks neater

 mattpi May 22nd, 2009 02:48 PM

You are partly correct - the expression will be negative for some values of $x.$ But not for all - what if $x>0?$

 mvho May 22nd, 2009 02:58 PM

Quote:
 ut not for all - what if
Hmm.. Not to sure. The question stated that, "For X<0 , simplify.." To be honest, I just threw the minus sign in there. Should it be plus/minus then?

Or, since it states, "For X<0, it should be a minus sign?

Confused. Thanks

 mattpi May 22nd, 2009 03:26 PM

Yep. Didn't spot the $x<0.$ My bad :oops:

You were right, as long as $x\leq-2.$

 mvho May 22nd, 2009 03:34 PM