很急 積分 √4-x² / x dx

2011-05-06 5:42 pm
積分 √4-x² / x dx

可以解答一下?

謝謝

回答 (2)

2011-05-06 6:13 pm
✔ 最佳答案
∫√(4-x^2)/x dx
Sol
Set x=2Siny
dx=2Cosydy
√(4-x^2)=2Cosy (不考慮負)
∫√(4-x^2)/x dx
=∫2Cosy/(2Siny)2Cosydy
=2∫Cos^2 y/Sinydy
=2∫(1-Sin^2 y)/Sinydy
=2∫Cscydy-2∫Sinydy
=2ln|Cscy-Coty|+2Cosy+c
=2ln|(2/x)-√(4-x^2)/x|+√(4-x^2)+c


2011-05-06 8:15 pm
http://www.wolframalpha.com/input/?i=y%3D%E2%88%AB%28%E2%88%9A4-x%C2%B2%29+%2F+x+dx

y=∫(√4-x²) / x dx
y = 2 log(x)-x^2/2


http://www.wolframalpha.com/input/?i=y%3D%E2%88%AB%5B%E2%88%9A%284-x%C2%B2%29%5D+%2F+x+dx
y=∫[√(4-x²)] / x dx
y == Sqrt[4 - x^2] + 2 Log[2 x] - 2 Log[2 + Sqrt[4 - x^2]]


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