→ ballballking:感謝 07/27 13:10
※ 引述《ballballking (蛋蛋王)》之銘言:
: (1) ∫y^2/(9-y^2)^(5/2)dy
: (2) lim f(x)/[x(arctanx)] =? f(x)= ∫e^(-t)/(1+t^2)dt 從0積到x^2
: x→0
: (3) 求x^(2/3)+y^(2/3)=1 的周長
1.
9 - y^2 = t^2 * y^2 => y = 3 * (t^2 + 1 )^(-1/2)
dy = - 3t * (t^2 + 1)^(-3/2) dt
9 1 -3t
=> ∫ --------- * ---------- * --------------- dt
t^2 + 1 t^5 * y^5 (t^2 + 1)^(3/2)
-27 (t^2 + 1)^(5/2)
= ∫ ---------------------- * ---------------- dt
t^4 * (t^2 + 1)^(5/2) 243
= 1/(27t^3) + C
= (1/27) * y^3 / (9 - y^2)^(3/2)
有錯還請不吝指正。
--
╬ ▃▃ ◢
◣
▄▄ ▄▄ ◥◣
▄▄ ╮ ◣
﹊ _ ▄ ▄ ◥◤
◣ ◢
--
※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 219.85.133.126
※ 文章網址: http://www.ptt.cc/bbs/Math/M.1406304221.A.D92.html
※ 編輯: a016258 (219.85.133.126), 07/26/2014 00:04:41