化簡無理式和求定積分問題
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化簡無理式和求定積分問題
2012-09-20 12:29 am
回答 (1)
2012-09-20 1:33 am
✔ 最佳答案
(a) 1/√(7+4√3)=1/√(7+2√12)
=1/√(4+2√12+3)
=1/(2+√3)
=2－√3
(b) ∫(0 to 2)_dx/√(16－x^2)
Set x=4Sinw
dx=4Coswdw
16－x^2=16－16Sin^2 w=16Cos^2 w
∫(0 to 2)_dx/√(16－x^2)
=∫(0 to π/3)_4Coswdw/4Cosw
=∫(0 to π/3)_dw
=π/3
收錄日期: 2021-05-02 10:49:28
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20120919000010KK04443