7.5 Logarithmic equations
Unit 7 · Exponential and logarithmic functions
Ideas in this lesson
Solve a single logarithm
Rewrite in exponential form, solve and check that the original argument is positive.
Combine two logarithms
Combine logs of the same base, solve the resulting equation and check every original argument.
Equal logarithms
Equal logs with the same valid base have equal positive arguments.
Reject extraneous roots
Algebraic candidates with a zero or negative original logarithm argument must be rejected.
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