困難對數函數問題 http://i707.photobucket.com/albums/ww74/stevieg90/IMG_6180_zpsqcv9l5ox.jpg?

2016-03-18 4:11 pm

回答 (1)

2016-03-22 2:06 pm
            2014
x = ────────────────────────────────
  (√2015 + 1)(∜2015 + 1)(⁸√2015 + 1)(¹⁶√2015 + 1)

Let ¹⁶√2015 = k , then
x = (k¹⁶ - 1) / [(k⁸ + 1)(k⁴+ 1)(k² + 1)(k + 1)]
x = (k⁸ - 1)(k⁸ + 1) / [(k⁸ + 1)(k⁴+ 1)(k² + 1)(k + 1)]
x = (k⁴- 1)(k⁴+ 1)(k⁸ + 1) / [(k⁸ + 1)(k⁴+ 1)(k² + 1)(k + 1)]
x = (k² - 1)(k² + 1)(k⁴+ 1)(k⁸ + 1) / [(k⁸ + 1)(k⁴+ 1)(k² + 1)(k + 1)]
x = (k - 1)(k + 1)(k² + 1)(k⁴+ 1)(k⁸ + 1) / [(k⁸ + 1)(k⁴+ 1)(k² + 1)(k + 1)]
x = k - 1
x + 1 = k
(x + 1)²º¹⁶ = k²º¹⁶
(x + 1)²º¹⁶ = ¹⁶√2015 ²º¹⁶
(x + 1)²º¹⁶ = 2015¹²⁶
2015ⁿ = 2015¹²⁶
n = 126


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原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20160318081159AAKexbq

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