Type I - Logarithm Bases

Authors Avatar

Math Portfolio- Logarithm Bases

Consider the following sequences: Find the nth term plus the general statement for each term.

Log2 8, Log4 8, Log8 8, Log16 8, Log32 8, ….

Firstly looking at this sequence the base value is the only number that changes throughout the sequence. The base of the logs in the sequence consists of:

2, 4, 8, 16, 32 …

This value is seems like it is doubling each time. This means that the next two values for the base is going to be:

32 × 2 = 64

64 × 2 = 128

However, when examining the sequence closely the base of the logs cannot be doubling because this means that the nth term is Log2n 8. This is invalid and wrong because if you substitute positive integers for n, the sequence does not appear to be the same. When adding the next two terms to the sequence, the sequence will look as shown:

 Log2 8, Log4 8, Log8 8, Log16 8, Log32 8, Log64 8, Log128 8, …

The nth term for this sequence is Log2n8. This can be simplified and written like this, Log2n23. This proves that the next two base values of the logs are 64 and 128 because 26 = 64 and 27 = 128.

The next sequence is:

Log3 81, Log9 81, Log27 81, Log81 81, …

In this sequence, when examining the base values for each term, the value is tripling; this means that the nth term is Log3n81. This means that the next two base values for the next two terms are 243 and 729. This is because 35 = 243, and 36 = 729. The next two terms for this sequence is added below:

Log3 81, Log9 81, Log27 81, Log81 81, Log243 81, …

The nth term can be simplified to be written as Log3n34.

The next sequence is:

Log5 25, Log25 25, Log125 25, Log625 25, …

In this sequence shown above, the base for each term is being multiplied by 5 each time, which shows that 5 can be to a power of n since 5 is being multiplied each time. In terms of the nth term, the number 5 is put to the power of n. The nth term is Log5n25. However, this can be simplified to be written as Log5n52. Therefore to find out the next two terms, terms 5 and 6, you will have to substitute for n. The bases of the logs for the next two terms are, 55 and 56 which equal, 3125 and 15625. Therefore when writing the next terms the numbers look like: Log312525 and Log1562525. The enhanced sequence will then be:

Join now!

Log5 25, Log25 25, Log125 25, Log625 25, Log312525, Log1562525, …

 Considering all of the above sequences, a further more generalized way for expressing the above sequences, can be written as:

Logmmk, Logm2mk, Logm3mk, Logm4mk, ...

The nth term for this sequence is Logmnmk. Analyzing this sequence the next two terms are going to be Logm5mk and Logm6mk, which therefore, makes this sequence:

Logmmk, Logm2mk, Logm3mk, Logm4mk, Logm5mk, Logm6mk, …

Logs can also be written in other ways as well. There are also many rules that logarithms can follow. In the form of   . For example, you can re-arrange the log function to become a fraction ...

This is a preview of the whole essay