Very simple log problem - I'm missing something.

[Zaent]

A=12^(1/5)
Log(A)=(1/5)Log(12)

The next part in the book says:

Log(A)=0.2158
A=1.644

I don't know how to do this without a calculator, and with a calculator I'm getting 1.24.

I'm doing e^0.2158

Can anyone please tell me where I'm going wrong here?Note: this isn't homework, just something I've come across

 

[bhillyard]

How old is the book? If old (pre 1980) then the expectation is that you have and use a set of log tables.

Also log(A) implies log to base 10 i.e. 10^.1258.
The standard notation for logs to base e is Ln(A).

 

[jedishrfu]

Your mistake is using e and not 10. Base e is used when doing stuff with natural logs ie ln() and 10 is used when doing base 10 logs.

Google can supplement a calculator if one isn't readily available.

The old fashioned way of solving log problems was to use precomputed log tables. Alternatively you could use the ll scales of a decitrig sliderule.

 

[Zaent]

Thank you both! I figured the book was old because it was asking me to do this, but I still knew my log knowledge was off somewhere. I'll remember the base 10 thing in future. Thanks again!

 

[CellCoree]

It seems like you are trying to solve for the value of A in the equation A=12^(1/5). To do this, you can use the property of logarithms which states that Log(a^b)=bLog(a). In this case, a=12 and b=1/5, so Log(A)=(1/5)Log(12).

Next, you can use a calculator to find the value of Log(12), which is approximately 1.0792. Then, you can plug this value into the equation Log(A)=(1/5)Log(12) and solve for Log(A).

Once you have the value of Log(A), you can use the inverse property of logarithms to find the value of A. In this case, you would take the antilog (or raise both sides to the power of 10) to get A=10^(Log(A)). Using a calculator, you should get A=1.644 as the final answer.

It seems like you may have made a mistake when using your calculator to find A. Make sure you enter the equation correctly and use the correct order of operations. It is also possible that the book made a mistake in their calculation of A=1.644. Double checking your work or using a different calculator may help you find the correct answer.