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