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#176 2013-07-27 11:31:58

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 83,251

Re: Simplify the following:

Hi;

I did that to get x all by itself on the left. What happened is I subtracted log(2) from both sides. That moved it over to the right side leaving a simpler expression on the left.

In case you are having some problems with balancing an equation check this out.

http://www.mathsisfun.com/algebra/add-s … lance.html


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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#177 2013-07-27 21:05:52

EbenezerSon
Member
Registered: 2013-07-04
Posts: 330

Re: Simplify the following:

Thank you very much bobbym for the link.
But there was xlog3 also present at the left side with the log2. Why didn't you balance the eqution with the log3 instead? because it was also present at the left side.

I just want to why you didnt use the log3 instead.

Thanks.


I know only one thing - that is that I know nothing

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#178 2013-07-27 21:09:20

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 83,251

Re: Simplify the following:

Hi;

If I were to move the x log(3) to the right side I would have to subtract x log(3) from both sides. Now I would have x on both sides. Remember I am trying to get x all byt itself and on one side.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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#179 2013-07-27 21:43:27

EbenezerSon
Member
Registered: 2013-07-04
Posts: 330

Re: Simplify the following:

Okay, but bobbym, the law logx-logy= logx/logy.
If it had been, logy-logy=0, is the zero?

If the logs have the same figures, it not right for one to divide?
But rather subtraction must take place?


I know only one thing - that is that I know nothing

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#180 2013-07-27 22:04:02

EbenezerSon
Member
Registered: 2013-07-04
Posts: 330

Re: Simplify the following:

You had your final answer by this:

x = log2/log2+log3
= 1.477

But I cant tell why the has, 0.39


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#181 2013-07-27 22:16:07

EbenezerSon
Member
Registered: 2013-07-04
Posts: 330

Re: Simplify the following:

Please, see how I solved the following:

2^x +2^-x=2.
bases are the same, therefore equate the exponents.
x-1-x =1
= x-x-1=1
=0-1 =1
=0 = 1+1
=0=2.

Is that right?
I think bases are the same, so doesnt need logarithm application.

Last edited by EbenezerSon (2013-07-27 22:35:16)


I know only one thing - that is that I know nothing

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#182 2013-07-27 23:08:11

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 83,251

Re: Simplify the following:

Hi;

What answer did you get for x?

I would do it like this:

Multiple everything by 2^x to clear fractions out.

Factor the left side.

So

(2x-1) = 0 and (2x-1) =0

2x-1 = 0 then x = 0

2x-1 = 0 then x = 0

x = 0 is the answer.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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#183 2013-07-28 01:59:51

EbenezerSon
Member
Registered: 2013-07-04
Posts: 330

Re: Simplify the following:

I had zero as the answer.

But as I am looking through the book, I chanced on the following, which I have solved but one of the answers was impossible to get. And the book had zero with that answer.

3^x + 3^-1=4.

My final answers are, x=1, and the impossible answer, 3^x=4.


I know only one thing - that is that I know nothing

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#184 2013-07-28 02:03:09

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 83,251

Re: Simplify the following:

Hi;

I am afraid x = 1 is incorrect.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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#185 2013-07-28 04:28:04

EbenezerSon
Member
Registered: 2013-07-04
Posts: 330

Re: Simplify the following:

The  book has x=0 or 1 as answer at its back.


I know only one thing - that is that I know nothing

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#186 2013-07-28 04:32:22

EbenezerSon
Member
Registered: 2013-07-04
Posts: 330

Re: Simplify the following:

How then would one solve this?


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#187 2013-07-28 05:37:05

EbenezerSon
Member
Registered: 2013-07-04
Posts: 330

Re: Simplify the following:

Okay, I admit, then see my thoughful manipulation:

3^x + 3^x-1= 4
multiplying 3 through.
3*3^x + 3^x*1/3 = 4* 3.
Let 3^x=m. therefore,
=3m + m = 12
= 4m - 12 =
0

factorising.
= 4(m-3) =0.
Is this correct?


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#188 2013-07-28 12:00:42

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 83,251

Re: Simplify the following:

Hi;

What did you get for x?


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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#189 2013-07-29 07:55:32

EbenezerSon
Member
Registered: 2013-07-04
Posts: 330

Re: Simplify the following:

The final result is my answer


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#190 2013-07-29 07:59:43

EbenezerSon
Member
Registered: 2013-07-04
Posts: 330

Re: Simplify the following:

I have considered it carefully, but see no way to solve than what I have done, please assist.

Thanks.


I know only one thing - that is that I know nothing

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#191 2013-07-29 08:18:27

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 83,251

Re: Simplify the following:

Hi;

Factor out a 3^(x-1) from each term on the left.


Divide both sides by 4.

Take log of both sides, you get.

(x-1) log(3) = 0

Divide both sides by log(3)

x - 1 = 0

x = 1

See you later, I need to do some chores and shopping.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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#192 2013-07-29 09:21:50

EbenezerSon
Member
Registered: 2013-07-04
Posts: 330

Re: Simplify the following:

bobbym wrote:

Hi;

Factor out a 3^(x-1) from each term on the left.

I don't understand how you factored it out.


I know only one thing - that is that I know nothing

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#193 2013-07-29 15:27:17

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 83,251

Re: Simplify the following:

Hi;

3* 3^(x-1) = 3^x


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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#194 2013-08-03 06:02:36

EbenezerSon
Member
Registered: 2013-07-04
Posts: 330

Re: Simplify the following:

Please check, the following for me.

Log(2x+3)=log4.
I had 20 as the answer, the has 10.

If 2logy-log2x=2log(y-x), express y in terms of x. I had (y-x)(y-2x^2). The book has y^-4xy+4^2x=0.


log(10+9x)-log(11-x)=2. I had 20 as answer, the book has 10.


Last but not the least
log81/log3^1.
the  book has -4 at its back as the answer.

Thanks.

Please, check the above if the answers are right. Me vs the book. -:)

Last edited by EbenezerSon (2013-08-03 07:20:08)


I know only one thing - that is that I know nothing

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#195 2013-08-03 06:06:26

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 83,251

Re: Simplify the following:

Hi;

Log(2x+3)=log4.
I had 20 as the answer, the has 10.

You had what for x?


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Offline

#196 2013-08-03 06:24:05

EbenezerSon
Member
Registered: 2013-07-04
Posts: 330

Re: Simplify the following:

I had 20.
The book has 10 as the answer
Sorry I supposed to have checked the writings before posting.

Thanks.


I know only one thing - that is that I know nothing

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#197 2013-08-03 06:25:30

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 83,251

Re: Simplify the following:

Both answers are wrong. The correct answer is 1.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Offline

#198 2013-08-03 06:29:19

EbenezerSon
Member
Registered: 2013-07-04
Posts: 330

Re: Simplify the following:

how about if the log4 were to be log45. What would the answer be?

Thanks.


I know only one thing - that is that I know nothing

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#199 2013-08-03 06:34:50

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 83,251

Re: Simplify the following:

You mean log(45) then x = 21.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Offline

#200 2013-08-03 06:53:42

EbenezerSon
Member
Registered: 2013-07-04
Posts: 330

Re: Simplify the following:

I
thanks, but please see the rest if they are right with their respective answers from the book, and my answers as well.


I know only one thing - that is that I know nothing

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