推 revengeiori : 非常感謝QAQ 01/15 03:22
※ 編輯: Tiderus (123.240.91.95), 01/15/2016 14:52:02
※ 引述《revengeiori (大笨宗)》之銘言：
: 如圖
: http://i.imgur.com/VexglHE.jpg
: 右邊有點不太清楚
: 求 |f(x) - g(x)| + |f(x) + g(x)| = 3 之解
: 麻煩大家了
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: Sent from JPTT on my Sony C6902.
｜log_x(4)-(1+log_x(3))｜ + ｜log_x(4)+(1+log_x(3))｜ = 3
|log_x(4/3x)| + |log_x(12x)| = 3
I.
log_x(4/3x) + log_x(12x) = ±3
16 = x^3 => x = 2^(4/3)
16 = x^(-3) => x = 2^(-4/3)
II.
log_x(4/3x) - log_x(12x) = ±3
1/9x^2 = x^3 => x = 3^(-2/5)
1/9x^2 = x^(-3) => x = 9
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※ 編輯: Tiderus (123.240.91.95), 01/15/2016 02:42:44