(6561)(1/2) + (6561)(1/4) + (6561)(1/8)

2025

(6561)(1/2) + (6561)(1/4) + (6561)(1/8)

  1. A.

    89

  2. B.

    90

  3. C.

    67

  4. D.

    93

Show answer & explanation

Correct answer: D

For a positive base expressed as a power of a smaller number, a fractional exponent b(k/n) equals the n-th root of bk; equivalently, (ak)(1/n) = a(k/n). Rewriting a large number as a power of a prime turns tricky roots into simple exponent division, avoiding messy root calculations.

Here 6561 = 38, so each term becomes:

  1. 6561(1/2) = (38)(1/2) = 3(8/2) = 34 = 81

  2. 6561(1/4) = (38)(1/4) = 3(8/4) = 32 = 9

  3. 6561(1/8) = (38)(1/8) = 3(8/8) = 31 = 3

  4. Adding the three values: 81 + 9 + 3 = 93

Cross-check: since 34 = 81, squaring gives 812 = 6561, confirming 38 = 6561 and that 6561(1/2) = 81. The sum of all three terms is 93.

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