Author Topic: Tips for evaluating logs without a calculator? (Read 1083 times)

shamester · May 05, 2015, 01:07:04 PM

Quote from: sorrel on May 05, 2015, 01:02:08 PM

I took the quiz I knew all of them except didn't know what to do with ln(e) and I put 10. But after googling it was 1
Darn

But thanks guys!

Ln(e) isn't 1, e is a button on your calculator, an infinite number kinda like Pi
-- it's the same process as LOG with Ln(e) except instead of putting 10 or what ever the base is, you put e^x
And in order to find this, you need a calculator or else you have to memorize a bunch of charts and table of values.

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Ipquarx · May 05, 2015, 01:50:56 PM

Quote from: shamester on May 05, 2015, 01:07:04 PM

Ln(e) isn't 1

Ln is the base e logarithm, therefore by definition Ln(e) is one, since e^1 = e.

phflack · May 05, 2015, 02:47:17 PM

Quote from: shamester on May 05, 2015, 01:07:04 PM

Ln(e) isn't 1, e is a button on your calculator, an infinite number kinda like Pi
-- it's the same process as LOG with Ln(e) except instead of putting 10 or what ever the base is, you put e^x
And in order to find this, you need a calculator or else you have to memorize a bunch of charts and table of values.

saying ln(e) != 1 is like saying log(10) != 1 or lg(2) != 1
which is like saying e^1 != e, 10^1 != 10, 2^1 != 2
but they're all true

you should refresh your memory on logs

Headcrab Zombie · May 05, 2015, 02:48:06 PM

Quote from: shamester on May 05, 2015, 01:07:04 PM

an infinite number kinda like Pi

Irrational*

Ragequit · May 05, 2015, 03:15:09 PM

use a tape measure and a note pad

Ipquarx · May 05, 2015, 03:23:41 PM

Quote from: Headcrab Zombie on May 05, 2015, 02:48:06 PM

Irrational*

Transcendental is also another one

shamester · May 05, 2015, 06:06:51 PM

Quote from: Ipquarx on May 05, 2015, 01:50:56 PM

Ln is the base e logarithm, therefore by definition Ln(e) is one, since e^1 = e.

Quote from: phflack on May 05, 2015, 02:47:17 PM

saying ln(e) != 1 is like saying log(10) != 1 or lg(2) != 1
which is like saying e^1 != e, 10^1 != 10, 2^1 != 2
but they're all true

you should refresh your memory on logs

Yes but I'm trying to tell OP that just because it has a base e doesn't mean it's 1, I thought that's what OP said. I understand LOGs I am just trying to clarify.

SeventhSandwich · May 05, 2015, 06:25:55 PM

Quote from: �l��kf�ce on May 05, 2015, 08:06:43 AM

can you explain this to me? i'm not in algebra but i like to know stuff

Mathematicians invent operators for stuff they can't describe in other ways. When ancient mathematicians needed a way to describe a series of added numbers, they invented the multiplication operator. When mathematicians needed a way to describe a series of multiplied numbers, they invented the exponent.

One of the flaws of the exponent is say I'm given something like this:
3²
This is pretty easy to compute. Just 3*3 = 9

But let's say that we're given 9 and want to know what exponent on 3 we need to 'make' 9.

There's no intrinsic way of doing this besides dividing by 3 over and over, and even that falls apart when you're asked something like 10^x = 2384.281.

Hence the logarithm.

Quote from: shamester on May 05, 2015, 01:07:04 PM

Ln(e) isn't 1, e is a button on your calculator, an infinite number kinda like Pi
-- it's the same process as LOG with Ln(e) except instead of putting 10 or what ever the base is, you put e^x
And in order to find this, you need a calculator or else you have to memorize a bunch of charts and table of values.

ignore this guy he has literally no idea what he's talking about