Reading a Log
Part of the Exponentials, Logs & Sequences section of Coddy's Algebra 2 journey. Lesson 17 of 49.
To read a log, turn it into a power question. log_3(81) asks: which power of 3 gives 81? Multiply 3 by itself and count: 3, 9, 27, 81. That took four 3s, so 3^4 = 81 and log_3(81) = 4.
A log and a power are two ways to write one fact, so you can always check a log by raising the base to it. If you think log_4(64) is 3, check it: 4^3 = 64, so it is.
Base 10 has a shortcut: count the zeros. log(10000) = 4, because 10000 is 1 followed by four zeros, which is 10^4.
Challenge
The board holds log_2(32). Work out its value, type it in the box under the problem, then press Check.
Try it yourself
Simplify the expression
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
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