Question 1207693
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2 < x < 4

Substitute the greatest lower bound of x, which is 2  1/(2-6) = -1/4 
and the least upper bound of x, which is 4.   1/(4-6) = -1/2

Since 1/(x-6) is continuous and decreasing for x < 6, it's approaching -1/2 from
below as x approaches 4 from the left, and approaching -1/4 as x approaches 2
from the right,  

-1/2 < 1/(x - 6) < -1/4 

Edwin</pre>