2x5^2-a=5+5^a?
回答 (2)
2015-10-29 11:15 am
2x5^(2-a) = 5 + 5^a
5^(2-a) + 5^(2-a) = 5^1 + 5^a
5^[(2-a) +(2-a)] = 5^(1+a)
=> 4-2a = 1+a (by comparing indices)*
=> 3 = 3a
=> a = 1
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
* comparing indices = 比對系數
5^(2-a) + 5^(2-a) = 5^1 + 5^a
5^[(2-a) +(2-a)] = 5^(1+a)
=> 4-2a = 1+a (by comparing indices)*
=> 3 = 3a
=> a = 1
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
* comparing indices = 比對系數
2015-10-29 9:43 am
2*5^(2-a)=5+5^a
==>2*5^2/5^a -5^a=5
==>50-(5^a)^2=5*5^a
==>(5^a +10)(5^a -5)=0
==>5^a=5(或5^a=-10不合)
==>a=1
==>2*5^2/5^a -5^a=5
==>50-(5^a)^2=5*5^a
==>(5^a +10)(5^a -5)=0
==>5^a=5(或5^a=-10不合)
==>a=1
收錄日期: 2021-05-03 15:27:28
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20151029010523AAKJeHk