- #1

mr_coffee

- 1,629

- 1

Hello everyone.

This is for a descrete math class, and he said you must know the change of base formula, so if you have everything in log base 3, you can figure out what it is in log base 2 as an example.

But I'm looking up the examples on the interenet and they all seem to convert whatever log they have to log base 10 and evaluate from there. Is this also what he would be talking about? No calculators are allowed to evaluate the logs.

Here is the change of base formula:

http://www.icoachmath.com/SiteMap/images/clip_image012_001.gif

and here is the example I'm looking at:

http://www.icoachmath.com/SiteMap/images/clip_image014_002.gif Okay i see that x = 4, and z = 8, but what is the base y? is the base y the new base you are trying to convert the orginal base into? FOr this example, you are given a base 4 log, and your trying to convert it to a log of base 2 and evaluate the answer I'm assuming right?

how did they end up with 3/2 though?

EDIT: I figured out how they got 3/2, i forgot about the other form of logs, 2^3 = 8, and 2^2 = 4.

Another example:

Use the change of base formula to evaluate

http://www.icoachmath.com/SiteMap/images/clip_image002_084.gif Choices:

A. 4.56

B. 4.86

C. 0.21

D. 5.16

Correct Answer: B

Solution:

Step 1:http://www.icoachmath.com/SiteMap/images/clip_image002_085.gif

Also is it up to you what base you convert it too? I see they used base 10 but there was no base 10 in the orginal problem.

how did they get: 2.43 from log_10(29)/log_10(4) ?I know this is algebra stuff but its been awhile

Thanks~

This is for a descrete math class, and he said you must know the change of base formula, so if you have everything in log base 3, you can figure out what it is in log base 2 as an example.

But I'm looking up the examples on the interenet and they all seem to convert whatever log they have to log base 10 and evaluate from there. Is this also what he would be talking about? No calculators are allowed to evaluate the logs.

Here is the change of base formula:

http://www.icoachmath.com/SiteMap/images/clip_image012_001.gif

and here is the example I'm looking at:

http://www.icoachmath.com/SiteMap/images/clip_image014_002.gif Okay i see that x = 4, and z = 8, but what is the base y? is the base y the new base you are trying to convert the orginal base into? FOr this example, you are given a base 4 log, and your trying to convert it to a log of base 2 and evaluate the answer I'm assuming right?

how did they end up with 3/2 though?

EDIT: I figured out how they got 3/2, i forgot about the other form of logs, 2^3 = 8, and 2^2 = 4.

Another example:

Use the change of base formula to evaluate

http://www.icoachmath.com/SiteMap/images/clip_image002_084.gif Choices:

A. 4.56

B. 4.86

C. 0.21

D. 5.16

Correct Answer: B

Solution:

Step 1:http://www.icoachmath.com/SiteMap/images/clip_image002_085.gif

Also is it up to you what base you convert it too? I see they used base 10 but there was no base 10 in the orginal problem.

how did they get: 2.43 from log_10(29)/log_10(4) ?I know this is algebra stuff but its been awhile

Thanks~

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