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Consider the following statements. For a...

Consider the following statements. For any integer n,
I. `n^(2)+3` is never divisible by 17.
II. `n^(2)+4` is never divisible by 17.
Then

A

both I and II are true

B

both I and II are false

C

I is false and II is true

D

I is true and II is false

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to analyze each statement regarding the divisibility of the expressions \( n^2 + 3 \) and \( n^2 + 4 \) by 17 for any integer \( n \). ### Step 1: Analyze Statement I - \( n^2 + 3 \) We need to determine if \( n^2 + 3 \) is never divisible by 17 for any integer \( n \). 1. **Calculate \( n^2 \mod 17 \)**: The possible values of \( n^2 \mod 17 \) can be found by squaring the integers from 0 to 16 (since these represent all possible residues modulo 17). - \( 0^2 \equiv 0 \) - \( 1^2 \equiv 1 \) - \( 2^2 \equiv 4 \) - \( 3^2 \equiv 9 \) - \( 4^2 \equiv 16 \equiv -1 \) - \( 5^2 \equiv 8 \) - \( 6^2 \equiv 2 \) - \( 7^2 \equiv 15 \equiv -2 \) - \( 8^2 \equiv 13 \equiv -4 \) - \( 9^2 \equiv 13 \equiv -4 \) - \( 10^2 \equiv 15 \equiv -2 \) - \( 11^2 \equiv 2 \) - \( 12^2 \equiv 8 \) - \( 13^2 \equiv -1 \) - \( 14^2 \equiv 9 \) - \( 15^2 \equiv 4 \) - \( 16^2 \equiv 1 \) The possible values of \( n^2 \mod 17 \) are: \( 0, 1, 2, 4, 8, 9, 13, 15, 16 \). 2. **Add 3 to each residue**: Now we add 3 to each of these values and check if any of them is congruent to 0 modulo 17. - \( 0 + 3 \equiv 3 \) - \( 1 + 3 \equiv 4 \) - \( 2 + 3 \equiv 5 \) - \( 4 + 3 \equiv 7 \) - \( 8 + 3 \equiv 11 \) - \( 9 + 3 \equiv 12 \) - \( 13 + 3 \equiv 16 \) - \( 15 + 3 \equiv 1 \) - \( 16 + 3 \equiv 2 \) None of these results is congruent to 0 modulo 17. Therefore, \( n^2 + 3 \) is never divisible by 17. ### Conclusion for Statement I: **Statement I is true.** ### Step 2: Analyze Statement II - \( n^2 + 4 \) Now we check if \( n^2 + 4 \) is never divisible by 17 for any integer \( n \). 1. **Add 4 to each residue**: We take the same residues of \( n^2 \mod 17 \) and add 4 to each. - \( 0 + 4 \equiv 4 \) - \( 1 + 4 \equiv 5 \) - \( 2 + 4 \equiv 6 \) - \( 4 + 4 \equiv 8 \) - \( 8 + 4 \equiv 12 \) - \( 9 + 4 \equiv 13 \) - \( 13 + 4 \equiv 17 \equiv 0 \) (This is divisible by 17) - \( 15 + 4 \equiv 19 \equiv 2 \) - \( 16 + 4 \equiv 20 \equiv 3 \) We find that when \( n^2 \equiv 13 \mod 17 \) (which occurs when \( n \equiv 4 \) or \( n \equiv 13 \)), \( n^2 + 4 \equiv 0 \mod 17 \). Therefore, \( n^2 + 4 \) can be divisible by 17. ### Conclusion for Statement II: **Statement II is false.** ### Final Answer: - Statement I is true. - Statement II is false.

To solve the problem, we need to analyze each statement regarding the divisibility of the expressions \( n^2 + 3 \) and \( n^2 + 4 \) by 17 for any integer \( n \). ### Step 1: Analyze Statement I - \( n^2 + 3 \) We need to determine if \( n^2 + 3 \) is never divisible by 17 for any integer \( n \). 1. **Calculate \( n^2 \mod 17 \)**: The possible values of \( n^2 \mod 17 \) can be found by squaring the integers from 0 to 16 (since these represent all possible residues modulo 17). ...
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