Domenick S. answered 10/15/13
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To start, we can rewrite X-2 as 1/X2 . If X is a positive number, then we will have 1/(X2) which is just a positive fraction. If X is a negative number, then we will have 1/( -X * -X). Since the product of two negative numbers is a positive number: 1/( -X * -X) = 1/(X2) which is just a positive fraction. So it doesn't matter whether X is positive or negative, X-2 will always be positive (when X is a nonzero real number).