QR Log help

[matty675]

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I'm having trouble with the logs in the QR section. I have no problems calculating the log of a number in order to find pH/pOH in the GC section, but the variables in QR keep throwing me off. I have watched quite a few videos on the laws of logarithms as well as Chad's but it seems like every couple of MD tests I am seeing some log function that I cannot solve for.

 

[NewBee12]

It will be helpful if you post a problem or 2.

 

[matty675]

For example: If a= log7b^7, then what is the value of 7^a?

There are multiple types of problems though. I guess I am looking for a set of hard and fast rules that will allow me to solve all of them.

 

[panmit]

hey matty, just keep on practicing with a wide variety of problems. I watched Chad's QR video on logs and just practiced on a bunch of problems. Pretty soon, there are only so many ways a question could be asked. So just keep practicing hard.

For example, the question you are talking about is relatively easy once you get the basics down. Majority of the problems we see about logs are mostly in base 10. However this one is in base 7. In order to get rid of the log, we just multiply 10^x. So let's work with base 10 in this example and pretend it says a= log10b^7 and we have to find 10^a. Just multiply 10^a on both sides to get rid of the log and we get 10^a=b^7.

The only thing different is the base. In this example to get rid of the log we multiply 7^x on both sides and we get 7^a = b^7.