F.4 Maths-Exponential Function
回答 (2)
2009-11-08 9:24 pm
✔ 最佳答案
5^-kx=8(5^x)^(-k) = 8
0.5^(-k) = 8
[2^(-1)]^(-k) = 8
2^(-1 * -k) = 8
2^k = 8
2^k = 2^3
k = 3
2009-11-08 10:14 pm
X = log 0.5/log5 = -0.431; and
kX = log 8/log 5 = 1.292.
therefore, k = 1.292/-0.431 =-2.997
= -3 (round up to nearest integer);
(Proof 5^-0.431 = 0.5 and 5^1.292 = 8)
kX = log 8/log 5 = 1.292.
therefore, k = 1.292/-0.431 =-2.997
= -3 (round up to nearest integer);
(Proof 5^-0.431 = 0.5 and 5^1.292 = 8)
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