52332111
Evaluate each expression or solve for \(x\).
a) \(\log_2(128)\)
b) \(\log_3\left(\frac{1}{9}\right)\)
c) \(4\log_{10}(0.1)\)
d) \(\log_5(x) = 2\)
e) \(3\log_2(x) = 12\)
Hints
- Rewrite a logarithmic statement as an exponential statement.
- Ask which exponent on the base produces the argument.
- Express fractions and decimals as powers with negative exponents.
- Isolate the logarithm before solving a logarithmic equation.
Solution
1. a) Since \(2^7 = 128\), \(\log_2(128) = 7\).
2. b) Since \(3^{-2} = \frac{1}{9}\), \(\log_3\left(\frac{1}{9}\right) = -2\).
3. c) Since \(10^{-1} = 0.1\), \(\log_{10}(0.1) = -1\). Therefore, \(4 \cdot (-1) = -4\).
4. d) Rewrite the equation as \(x = 5^2\), so \(x = 25\).
5. e) Divide by \(3\) to get \(\log_2(x) = 4\). Then \(x = 2^4 = 16\).
Answer
a) \(7\)
b) \(-2\)
c) \(-4\)
d) \(x = 25\)
e) \(x = 16\)
