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#626 2014-09-27 09:01:30

EbenezerSon
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Registered: 2013-07-04
Posts: 554

Re: Simplify the following:

Then that would be decimal numbers I think.


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#627 2014-09-27 09:02:06

bobbym
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From: Bumpkinland
Registered: 2009-04-12
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Re: Simplify the following:

That is correct. I am going to eat see you in a half hour.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#628 2014-09-28 04:47:59

EbenezerSon
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Registered: 2013-07-04
Posts: 554

Re: Simplify the following:

Now before I proceed on the decimals, let me endeavour to put this across c'os I am getting zero as an answer to this and the book seems to have 1/4 ;

logx - 4logx = 2

The LHS is having 8 as their bases

Thank you!

Last edited by EbenezerSon (2014-09-28 04:49:05)


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#629 2014-09-28 07:50:48

bobbym
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From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Simplify the following:

Hi;

I am getting 1 / 4 as well.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#630 2014-09-28 23:39:52

EbenezerSon
Member
Registered: 2013-07-04
Posts: 554

Re: Simplify the following:

Is 8  not going to raise the power 2 at the RHS?


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#631 2014-09-28 23:41:09

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Simplify the following:

First algebraically clean it up a bit.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#632 2014-09-28 23:49:30

EbenezerSon
Member
Registered: 2013-07-04
Posts: 554

Re: Simplify the following:

Like this?

x - x^4 = 8^2


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#633 2014-09-28 23:55:52

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Simplify the following:

logx - 4logx = 2


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#634 2014-09-29 01:00:19

EbenezerSon
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Registered: 2013-07-04
Posts: 554

Re: Simplify the following:

bobbym wrote:

logx - 4logx = 2


wierd to me though


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#635 2014-09-29 01:09:05

bobbym
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From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Simplify the following:

If you had 1 apple and you took 4 apples away you would have -3 apples. 1 log(x) - 4 log(x) = 3 log(x). 1 of anything - 4 of the same thing is -3 of that thing.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#636 2014-09-29 01:12:45

EbenezerSon
Member
Registered: 2013-07-04
Posts: 554

Re: Simplify the following:

How I did it was;

log(x/x^4) = 8^2
taking antilog
x = 64x^4

[I was rather thinking that minus sign in logarithm means a division sign, what do you say to this?]


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#637 2014-09-29 01:21:04

bobbym
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From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Simplify the following:

That is not correct. When you take the anti-log, you have to take it of both sides.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#638 2014-09-29 01:42:13

EbenezerSon
Member
Registered: 2013-07-04
Posts: 554

Re: Simplify the following:

bobbym wrote:

logx - 4logx = 2


I'm now grasping it - how are you gonna proceed from here?


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#639 2014-09-29 01:48:23

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Simplify the following:

Divide both sides by -3.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#640 2014-09-30 02:37:21

EbenezerSon
Member
Registered: 2013-07-04
Posts: 554

Re: Simplify the following:

I see now, but do you agree that a minus sign in logarithm means one has to divide?


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#641 2014-09-30 04:09:16

bobbym
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From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Simplify the following:

Yes, that is the reason tjhey were invented for.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#642 2014-09-30 04:42:51

EbenezerSon
Member
Registered: 2013-07-04
Posts: 554

Re: Simplify the following:

If so, then I was thinking the steps should be;

logx - 4logx = 2
log(x/x^4) = log8^2
taking antilog of both sides
x/x^4 = 8^2
x = 64x^4

What do you say to this?


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#643 2014-09-30 04:52:49

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Simplify the following:

It is not correct. Where does log8^2 come from?


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#644 2014-10-01 04:55:46

EbenezerSon
Member
Registered: 2013-07-04
Posts: 554

Re: Simplify the following:

bobbym wrote:

Where does log8^2 come from?

That's according to the difinition of logarithm
- "the logarithm of any number b to the base a is the index or power to which the base must be raised to give the number" example ; 
log b = c [taking 'a' as the base] =  b = a^c

Last edited by EbenezerSon (2014-10-01 04:57:57)


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#645 2014-10-01 06:06:34

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Simplify the following:

That is written


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#646 2014-10-01 21:03:38

EbenezerSon
Member
Registered: 2013-07-04
Posts: 554

Re: Simplify the following:

There was a similar problem in the book, and there was 1 at the right hand side of the equation,  and in the course of manipulation it became [log10] and when antilog was taken it became 10. So that's the idea I tried using it. I don't know if you understand what I am putting across.

Hi; this is the problem I spoke of above, that used the one I understand;

log(x^2 + 1 ) - 2logx = 1
log(x^ + 1/ x^2) = log10
x^ + 1/x^2 = 10
x^2 + 1 = 10x^2
9x^2  = 1
x^2 = 1/9
x = +1/3

Please, see the method - this is the one I wanted to use for the one under discussion

Last edited by EbenezerSon (2014-10-17 01:19:26)


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#647 2014-10-01 21:15:04

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Simplify the following:

I understand but it leads to the wrong answer, therefore I would drop it.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#648 2014-10-04 06:20:26

EbenezerSon
Member
Registered: 2013-07-04
Posts: 554

Re: Simplify the following:

Okay, I will let you see that problem yourself.

In one of the rules of logarithm it says, log(m/n) equal log m - log n, so I was expecting you would say logx - 4logx would be log(x/x^4). But couldn't understand why you subtracted logx from 4logx.


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#649 2014-10-04 06:23:33

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Simplify the following:

There is nothing wrong with your idea except that because it is complicated you are making some mistake on the next line.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#650 2014-10-04 06:31:13

EbenezerSon
Member
Registered: 2013-07-04
Posts: 554

Re: Simplify the following:

Please, if you would not mind use my idea to solve, because I am rather familiar with that idea.

Thank you very much


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