Answer: 6 or −4.
- A 6 only
- B 6 or −4
- C 4 or −6
- D 5 or −5
Correct answer: B. 6 or −4
Explanation: Only z differs, so |a − 1| = 5, giving a − 1 = ±5 and hence a = 6 or a = −4.
Concept context
Coordinate axes and planes in space, octants, distance between two points, and the section formula
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