緊急!!F.4 MATHS 求解答,15點!!
回答 (3)
2012-12-29 7:33 am
✔ 最佳答案
Solve the exponential equation 4^x+4^(x－2)=34Sol
Set y=4^(x－2)
16y=4^x
16y+y=34
y=2
4^(x－2)=2
x－1=1/2
x=5/2
2012-12-29 11:40 pm
中四好像是在學對數（Logarithm）吧
其實除了兩位的方法外
用log 來 solve 也行的
4^x + 4^(x-2) = 34
(1+1/16)* 4^x = 34
log17 -log16 + xlog4 = log34
x = (log34 - log17 + log16) / log4
x = 2.5
其實除了兩位的方法外
用log 來 solve 也行的
4^x + 4^(x-2) = 34
(1+1/16)* 4^x = 34
log17 -log16 + xlog4 = log34
x = (log34 - log17 + log16) / log4
x = 2.5
2012-12-29 7:53 pm
Let y = 4^(x - 2)
4^x = 4^2 * 4^(x - 2) = 16y
So, 4^x + 4^x-2 = 34
16y + y = 34
y = 2
4^(x - 2) = 2
2^[2(x - 2)] = 2
2(x - 2) = 1
x - 2 = 1/2
x = 5/2
4^x = 4^2 * 4^(x - 2) = 16y
So, 4^x + 4^x-2 = 34
16y + y = 34
y = 2
4^(x - 2) = 2
2^[2(x - 2)] = 2
2(x - 2) = 1
x - 2 = 1/2
x = 5/2
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