Re: [理工] [工數]-ODE..
※ 引述《mdpming (+-*/)》之銘言:
: 1.
: y'' + 4y = tan2x
: 這題 yp 有人可以提示一下嗎..
: 我想知道用逆運算子的解法QQ
: 代定係數法我算過了QQ
: 2.
: 周易寫真密集 上策 p2-37頁
: 2 3
: 倒數第5行 的x 事不是打錯? 應該寫成 x ..
我也來提供一個
科科
yh = c1cos2t + c2sin2t
1
yp = ──[sin2x∫cos2x tan2xdx - cos2x∫sin2x tan2x dx]
2 2
1 -1 1-(cos2x)
= ── [──sin2xcos2x - cos2x∫ ────── ]
2 2 cos2x
1 1 cos2x
= ───[ - ──sin2xcos2x - ─── (ln│sec2x +tan2x│ -sin2x)
2 2 2
cos2x
=- ─── ln│sec2x + tan2x │
4
y = yh + yp
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 59.105.159.190
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※ 編輯: CRAZYAWIND 來自: 59.105.159.190 (12/07 22:48)
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1 1
───── R(x) = ──[sinax∫cosaxR(x)dx - cosax∫sinaxR(x)dx
D^2 + a^2 a
L(d)的工式
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※ 編輯: CRAZYAWIND 來自: 59.105.159.190 (12/07 22:51)
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