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Difficulty: 1/102022 NMTC 2022 (QII-39)

If is an integer in , which of the following statements is mathematically correct?

Options:

  • B.

  • C.

  • D.

Guide / Hint

Hint 1: Recall the definition: means for some integer .

Hint 2: Check if you can write as a product of and some integer.

Hint 3: Since is always true, is correct. This is at option index 0.

Solution

Step 1 (Understand the divisibility relation): An integer divides an integer (written ) if there exists an integer such that:

Step 2 (Test divisibility of zero): Let's test the number . For any non-zero integer , we want to find if there is an integer such that .
Choosing (which is a valid integer):

This equation is mathematically true for any non-zero integer . Therefore, divides , denoted as:

Step 3 (Analyze other options):

  • : Divisibility by zero is undefined.

  • : Only true if .

  • : Only true if .

Step 4 (Conclusion): The correct statement is , which is at option index 0.

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