Difficulty: Easy
Correct Answer: 8
Explanation:
Concept / Approach
Step-by-step derivation
(2k + 3)^2 − (2k + 1)^2 = [(2k + 3) − (2k + 1)] × [(2k + 3) + (2k + 1)]= (2) × (4k + 4) = 8(k + 1)
Conclusion
The expression is always a multiple of 8 (but not always 16), hence divisible by 8.
Final Answer
8
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