[F.4]Maths Log
回答 (3)
2015-03-02 2:44 am
✔ 最佳答案
3 [5^(2x- 1)] + 5^(2x) + 1 = 413 [5^(2x - 1)] + 5^[1 + (2x - 1)] = 40
3 [5^(2x - 1)] + 5 [5^(2x - 1)] = 40
(3 + 5) [5^(2x - 1)] = 40
8 [5^(2x - 1)] = 40
5^(2x - 1) = 5
2x - 1 = 1
2x = 2
x = 1
2015-03-02 8:37 pm
3(5²ˣ⁻¹)＋5²ˣ＋1＝41
==> 3(5²ˣ)＋5(5²ˣ)＋5＝205 ⋯⋯ (multiply each term by 5)
==> 8(5²ˣ)＝200
==> 5²ˣ＝25＝5²
∴ 2x＝2
==> x＝1
==> 3(5²ˣ)＋5(5²ˣ)＋5＝205 ⋯⋯ (multiply each term by 5)
==> 8(5²ˣ)＝200
==> 5²ˣ＝25＝5²
∴ 2x＝2
==> x＝1
2015-03-02 1:59 am
3 [ 5^(2x-1) ] + 5^(2x+1) = 41
or
3 [ 5^(2x) - 1 ] + 5^(2x) + 1 = 41 ?
or
3 [ 5^(2x) - 1 ] + 5^(2x) + 1 = 41 ?
收錄日期: 2021-04-15 18:24:09
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20150301000051KK00062