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2008-08-25 10:02 pm
✔ 最佳答案
2^(2x + 2) = 9. 2^x - 2.2^(2x) . 2^2 = 9.2^x - 2
2^(2x) . 4 = 9. 2^x - 2
4(2^x)^2 - 9. 2^x + 2 = 0
Let 2^x = y
4y^2 - 9y + 2 = 0
(4y -1)(y -2) = 0
y = 1/4 and 2.
That is 2^x = 1/4, so x = -2.
2^x = 2, so x =1.
2008-08-25 10:05 pm
2^(2x+2)=9(2^x)-2
4[2^(2x)]-9(2^x)+2=0
[4(2^x)-1](2^x-2)=0
2^x=1/4 or 2^x=2
2^x=2^-2 or 2^x=2^1
x=-2 or 1
4[2^(2x)]-9(2^x)+2=0
[4(2^x)-1](2^x-2)=0
2^x=1/4 or 2^x=2
2^x=2^-2 or 2^x=2^1
x=-2 or 1
收錄日期: 2021-04-25 22:36:10
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https://hk.answers.yahoo.com/question/index?qid=20080825000051KK01329