Khan Academy: Logarithm Properties: Change of Base Formula

For this logarithms worksheet, students solve 25 short answer problems.  Students use the change of base formula to solve each logarithmic expression in the calculator.

I can't calculate a base-2 logarithm since my calculator doesn't have a base-2 log key. Young mathematicians use the change of base formula to extend the properties of logarithms to all bases. Among these bases is the natural log base,...

This video proves the helpful change of base formula for logarithms. The proof steps may need to be more intuitive to most logarithm learners, but the algebraic manipulation shown using logs is interesting.

Explore logarithm properties through change of base formula proofs.

Demonstrates how to use the change of base formula to evaluate a given logarithm and proves the change of base formula. [7:32]

Introduction to the first two logarithm properties.

Using Multiple Logarithm Properties to Simplify

Proof of the logarithm property: log a + log b = log ab

Proofs of the logarithm properties: A(log B) = log (B^A) and log A - log B = log (A/B)

Logarithm of a Power