Answer:
(c) x ≤ 5 or x ≥ 7
Explanation:
You want the solution to |x -6| ≥ 1.
Unfold
The absolute value relation represents two relations, one for the domain x < 6, and one for the domain x ≥ 6.
x < 6
In this domain, the inequality becomes ...
-1 ≥ x -6
5 ≥ x . . . . . . add 6
x ≤ 5 . . . . . . . put x on the left
x ≥ 6
In this domain, the inequality is ...
x -6 ≥ 1
x ≥ 7
The disjoint solution sets are x ≤ 5 or x ≥ 7.
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Additional comment
For |x -a| ≤ b, we can "unfold" this to the compound inequality ...
-b ≤ (x -a) ≤ b
copying the inequality symbol to the left side, and writing the opposite of the constant there.
We can do the same thing with the inequality ...
|x -a| ≥ b
but it doesn't really make sense as a compound inequality.
Instead, we have to write it as ...
-b ≥ (x -a) or (x -a) ≥ b
in recognition of the fact that the solution spaces are disjoint.