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Year 11 · Functions & Graphs

Evaluate logarithms

A logarithm asks "what power?": log₂ 8 = 3 because 2³ = 8.

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How to do it

  1. Rewrite as a power question.
  2. Log laws: log a + log b = log ab; log a − log b = log (a ÷ b); n log a = log aⁿ.

Worked example

log_2(16) = ?
log_2(y) asks: 2 to what power equals y? 2^4 = 16, so the answer is 4.
Answer: 4

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log of 1 is always 0.

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