Concept

Summary of the Properties of Logarithms

The properties of logarithms provide a complete set of algebraic rules for evaluating, expanding, and condensing logarithmic expressions. For any valid base aa (a>0a > 0 and aeq1a eq 1), positive real numbers MM and NN, and any real number pp, the core properties are summarized as follows:

  • Logarithm of 11 Property: loga1=0\log_a 1 = 0 (Natural logarithm: ln1=0\ln 1 = 0)
  • Logarithm of the Base Property: logaa=1\log_a a = 1 (Natural logarithm: lne=1\ln e = 1)
  • Inverse Properties: alogax=xa^{\log_a x} = x and logaax=x\log_a a^x = x (Natural logarithm: elnx=xe^{\ln x} = x and lnex=x\ln e^x = x)
  • Product Property: loga(MN)=logaM+logaN\log_a(M \cdot N) = \log_a M + \log_a N (Natural logarithm: ln(MN)=lnM+lnN\ln(M \cdot N) = \ln M + \ln N)
  • Quotient Property: logaMN=logaMlogaN\log_a \frac{M}{N} = \log_a M - \log_a N (Natural logarithm: lnMN=lnMlnN\ln \frac{M}{N} = \ln M - \ln N)
  • Power Property: logaMp=plogaM\log_a M^p = p \log_a M (Natural logarithm: lnMp=plnM\ln M^p = p \ln M)

These properties are essential tools that will be very helpful when continuing to solve both exponential and logarithmic equations.

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Updated 2026-05-25

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Intermediate Algebra @ OpenStax

Ch.10 Exponential and Logarithmic Functions - Intermediate Algebra @ OpenStax

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