3^(x+2) - 3^x=72
6^-2x=(2^2-x)(3^2-x)
指數化簡問題
2007-08-07 9:22 pm
回答 (2)
2007-08-07 9:33 pm
✔ 最佳答案
3^(x+2) - 3^x=729 3^x - 3^x =72
8 3^x =72
3^x = 9
x =2
6^-2x=(2^2-x)(3^2-x) (是否2的2-x次乘3的2-x次???)
6^-2x=6^2-x
-2x = 2-x
x= -2
2007-08-07 9:48 pm
3^(x+2) - 3^x=72
3^(x+2) - 3^x-72=0
9(3^x)-3^x=72
8(3^x)=72
3^x=9
x=2
6^-2x=(2^2-x)(3^2-x)
(1/36)(6^x)=4[2^(-x)]9[3^(-x)]
6^x=36^2[6(-x)]
6^(2x)=36^2
36^x=36^2
x=2
3^(x+2) - 3^x-72=0
9(3^x)-3^x=72
8(3^x)=72
3^x=9
x=2
6^-2x=(2^2-x)(3^2-x)
(1/36)(6^x)=4[2^(-x)]9[3^(-x)]
6^x=36^2[6(-x)]
6^(2x)=36^2
36^x=36^2
x=2
參考: me
收錄日期: 2021-04-29 22:16:09
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https://hk.answers.yahoo.com/question/index?qid=20070807000051KK02022