這是一條積分既問題..{=積分符號..
k
{ 24/(1-4x)^3 dx = 35/3 Find k,where k<1/4
-1/2
ans:k=1/8
求步驟
數學高手請進！
2010-01-14 7:01 am
回答 (1)
2010-01-14 7:10 am
✔ 最佳答案
I = ∫ (-1/2 to k) 24/(1-4x)^3 dx = 35/3Let 1 - 4x = u
-4dx = du
x = -1/2, u = 3
x = k, u = 1 - 4k
So I = ∫(3 to 1-4k) -6u^(-3) du
= 3u^(-2) [3 to 1-4k]
= 3/(1-4k)^2 - 3/9 = 35/3
3/(1-4k)^2 = 36/3
(1-4k)^2 = 1/4
(1-4k)^2 - 1/2^2 = 0
(1-4k+1/2)(1-4k-1/2) = 0
(3/2-4k)(1/2-4k) = 0
k = 3/8 (rejected) or k = 1/8
收錄日期: 2021-04-23 23:28:07
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100113000051KK01811