呢題數要點樣做啊??
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呢題數要點樣做啊??
2011-04-18 3:48 am
回答 (2)
2011-04-18 3:59 am
✔ 最佳答案
(I) 令y = 0 => 2x^2 - 4x = 02x(x - 2) = 0
x = 2
因此x的取值範圍是0< x < 2
(II) 4x - 2x^2 = y^2
y = √(4x - 2x^2)
log x + log y
= log x + log √(4x - 2x^2)
= log √(4x^3 - 2x^4)
= (1/2)log(4x^3 - 2x^4)
當x = 1.5時﹐該式有最大值(1/2)log3.375
2011-04-18 11:16 pm
I)
2x^2 + y^2 - 4x = 0
2x^2 - 4x = -y^2 < 0 (since y^2 >0)
2x(x-2) < 0
0< x <2
2x^2 + y^2 - 4x = 0
2x^2 - 4x = -y^2 < 0 (since y^2 >0)
2x(x-2) < 0
0< x <2
收錄日期: 2021-04-26 14:06:10
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110417000051KK01150