You can
put this solution on YOUR website!
You can always write these out the long way
( if the numbers aren't very big ) and look at them

The main thing to notice is that there are an odd number of
(-2)'s and an even number of (-5)'s
Think of the (-2)'s grouped in pairs with one left over
(-2)*(-2) this is positive
(-2)*(-2) also positive
(-2) this is negative
So, you have (+) x (+) x (-) = (-)
---------------------------
What if it was

?
You would pair these up the same way, so you'd have
a bunch of (+) x (+) x (+) . . . etc and one (-) left. that would
give you a minus result
--------------------
Back to your problem, then

and

OK?