A>0 x>0 a^2-x^2=ax (a^2+x^2)/2ax=? 數學?
回答 (1)
2016-12-02 10:25 pm
✔ 最佳答案
(a² + x²) / (2ax) = (a/x + x/a) / 2
= √(a/x + x/a)² / 2 for a > 0 , x > 0
= √( (a/x - x/a)² + 4 ) / 2
= √( (a² - x²) / (ax) )² + 4) / 2
= √(1² + 4) / 2
= √5 / 2
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