Solve the equation \(4|5^x - 1| = 5^x\), giving your answers correct to 3 decimal places.
Solution
Start with the equation \(4|5^x - 1| = 5^x\).
This implies two cases: \(4(5^x - 1) = 5^x\) and \(4(1 - 5^x) = 5^x\).
For the first case, \(4(5^x - 1) = 5^x\):
\(4 imes 5^x - 4 = 5^x\)
\(3 imes 5^x = 4\)
\(5^x = \frac{4}{3}\)
Taking logarithms, \(x = \log_5\left(\frac{4}{3}\right)\).
For the second case, \(4(1 - 5^x) = 5^x\):
\(4 - 4 imes 5^x = 5^x\)
\(4 = 5^x + 4 imes 5^x\)
\(4 = 5 imes 5^x\)
\(5^x = \frac{4}{5}\)
Taking logarithms, \(x = \log_5\left(\frac{4}{5}\right)\).
Calculating these values gives \(x = 0.179\) and \(x = -0.139\).
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