Let k be a positive integer such that k + 4 is divisible by 7. Then the smallest positive integer n, greater than 2, such that k + 2n is divisible by 7 equals
Explanation:
a = k + 4 is divisible by 7
b = k + 2n is divisible by 7
⇒ b – a = 2n – 4 is divisible by 7
⇒ 2n – 4 = 0 or 7 or 14 ...
For minimum integral value of n, greater than 2
2n – 4 = 14
⇒ n = 9
Hence, option (a).
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