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- Sep 30th 2010, 03:13 PM #1

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- Sep 30th 2010, 03:17 PM #2

- Sep 30th 2010, 03:24 PM #3

- Sep 30th 2010, 04:17 PM #4

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- Oct 1st 2010, 03:03 AM #5

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Yet another way: x(x- 6)< -6 is the same as which is the same as (I used the fact that [tex]a^2- b^2= (a- b)(a+ b)).

The product of two numbers is negative if and only if one is positive and the other negative. Since the two factors are "x- 3" plus and minus the same thing, obviously . The first must be positive and the second negative: we must have and .

From the first and from the second . Together, those give, as before, .

klik11, you English is excellent. Certainly compared with my*(Put whatever language you want here)*!