大學數學，請問圈起來的題目要如何解?
回答 (1)
2015-10-02 11:25 am
✔ 最佳答案
h(x) = x^(1/2)*e^(-x)h' (x)
= (1/2)x^(-1/2)*e^(-x) + x^(1/2)*[ - e^(-x) ]
= e^(-x) * [ 1/(2√x) - √x ]
= e^(-x) * [ ( 1 - 2x )/(2√x) ]
When 0 < x < 1/2
h' (x) > 0 , so f is increasing
When x > 1/2
h' (x) < 0 , so f is decreasing
Ans: h(x) is increasing on ( 0 , 1/2 ) , and decreasing on ( 1/2 , ∞ )
收錄日期: 2021-05-02 14:08:52
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20151002030344AAOS22s