By what number should 81 be divided to get a perfect cube?

2024

By what number should 81 be divided to get a perfect cube?

  1. A.

    3

  2. B.

    6

  3. C.

    7

  4. D.

    More than one of the above

  5. E.

    None of the above

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Correct answer: A

Step 1: Factorize 81 into prime factors: 81 = 3 × 3 × 3 × 3 = 3^4.

Step 2: A perfect cube has exponents in its prime factorization that are multiples of 3.

Step 3: 3^4 has exponent 4, which is not a multiple of 3. To make it a perfect cube, reduce the exponent to the nearest multiple of 3, which is 3.

Step 4: Divide 3^4 by 3^1 to get 3^3, which is a perfect cube.

Step 5: Therefore, 81 must be divided by 3 to get a perfect cube.

हिन्दी उत्तर:

चरण 1: 81 को अभाज्य गुणनखंडों में विभाजित करें: 81 = 3 × 3 × 3 × 3 = 3^4।

चरण 2: एक पूर्ण घन में अभाज्य गुणनखंडों के घातांक 3 के गुणक होते हैं।

चरण 3: 3^4 में घातांक 4 है, जो 3 का गुणक नहीं है। इसे एक पूर्ण घन बनाने के लिए, घातांक को 3 के निकटतम गुणक, अर्थात् 3, तक कम करें।

चरण 4: 3^4 को 3^1 से विभाजित करने पर 3^3 प्राप्त होता है, जो एक पूर्ण घन है।

चरण 5: इसलिए, 81 को 3 से विभाजित करना चाहिए ताकि एक पूर्ण घन प्राप्त हो।

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