maths question- logarithm

madmikejt12 · #1 (**permalink**) 24-12-2007, 03:54 PM

does anybody know anything about these?

I have an asignment here and im baffled by this one:

Reduce the following to a single logarithm:

2log 2 - 3log 4 + log 6

could someone please show me how to do it?

also this one:

x= log4 2

(The RED "4" should be in subscript format but it is not working)

jephree · #2 (**permalink**) 24-12-2007, 06:52 PM

This should help on the first problem:

http://web.rollins.edu/~dchild/SMGSi...uide/Logs.html

The answer to the second is:

log4 2 = 0.50

(assuming base 10)

Many guides and calculators found with Google:

http://www.google.com/search?sourcei...f8&q=logarithm

...

madmikejt12 · #3 (**permalink**) 24-12-2007, 07:35 PM

Thanks for the reply

i got 0.5 for the second one before when i tries it, wasnt sure if it was right though...

i used:

Log10 2/Log10 4

Blue number= Base

I am still unsure about how to go about the 1st one

Do i need to make all the bases equal and then add them? if so how?
We didnt have time to go over logarithms on our college day, we were to buisy going over GCSE level stuff which i had already answered and the asignment is due in when we go back! (along with 5 others!!!)

Also what is Ln? Q4 is all about logarithms and indicies and the last part just says:

Solve for x
y=ln(x)

jephree · #4 (**permalink**) 24-12-2007, 07:54 PM

Quote:

natural logarithm (loge, ln, log, or Ln) in mathematical analysis, statistics, economics and some engineering fields. The reasons to consider e the natural base for logarithms, though perhaps not obvious, are numerous and compelling.
common logarithm (log10 or simply log; sometimes lg) in various engineering fields, especially for power levels and power ratios, such as acoustical sound pressure, and in logarithm tables to be used to simplify hand calculations
binary logarithm (log2; sometimes lg, lb, or ld) in information theory and computer-related fields
indefinite logarithm when the base is irrelevant, e.g. in complexity theory when describing the asymptotic behavior of algorithms in big O notation.

http://en.wikipedia.org/wiki/Logarithm

I used a calculator. I probably know less than you as it has been many years since I did this stuff.

I don't fully understand the notation:

2log 2 - 3log 4 + log 6

Unless it equates to log2 2 - log3 4 + log 6

Yet log 6 has no base

I didn't try this calculator but it appears to handle and simplify equations:

http://web.rollins.edu/~dchild/SMGSi...uide/Logs.html

madmikejt12 · #5 (**permalink**) 24-12-2007, 08:34 PM

Quote:

Yet log 6 has no base

the 6 is the base isnt it?

like the 2 and the 4
Nevermind that, im getting confused.... i dont have a clue really!!

i wrote it slightly wrong in the 1st post, there should be no spaces before the numbers:

2log2 - 3log4 + log6

In my notes it says "log bn"
Where b=base and is "subscripted"

DevilsAdvocate · #6 (**permalink**) 25-12-2007, 10:22 AM

And to think people reckon that these days the geeks shall inherit the earth... They've clearly never heard of John Napier, ÜberGeek!!

madmikejt12 · #7 (**permalink**) 28-12-2007, 04:11 PM

2log2-3log4+log6 can also be written as:

log2^2-log4^3+log6

Does this help? Still cant figure out what to do with it!!!

Tassie Devil · #8 (**permalink**) 29-12-2007, 12:51 AM

2log2 - (3log4 + log6) = -1.98

I had to wait for hubby to come home, I know zilch about this stuff. The above equation is how he entered it into a calculator. Hope it makes sense to you cause it doesn't to me.

madmikejt12 · #9 (**permalink**) 29-12-2007, 01:07 AM

Thank you for the reply

but sorry, the question is asking me to reduce it to a sinle logarithm

jephree · #10 (**permalink**) 29-12-2007, 01:43 AM

Using the formula for addition and subtraction I get this:

log(A) + log(B) -> log(A x B)

log(A) - log(B) -> log(A/B)

log2^2/4^3 + log6

log2^2/4^3 x 6

...perhaps the DA will send John Napier by this way.