What could x be in here?

Excuse me for my bad explanation, my English is bad.

Results 1 to 5 of 5

- Sep 30th 2010, 02:13 PM #1

- Joined
- Nov 2009
- Posts
- 56

- Sep 30th 2010, 02:17 PM #2

- Sep 30th 2010, 02:24 PM #3

- Sep 30th 2010, 03:17 PM #4

- Joined
- Nov 2009
- Posts
- 56

- Oct 1st 2010, 02:03 AM #5

- Joined
- Apr 2005
- Posts
- 19,340
- Thanks
- 2859

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)*!