Find the truth set of the following.

EbenezerSon · 2013-07-22 03:02:49

I have solved the following, but it seems impossible to factorise at some point:

3^2x+1 - 3^x+2 - 3^x+1 = 0.

The book says, x=-1 or -2
It was impossible for to factorise at some point, let alone getting the answer.

I need assistance.

Thanks.

Bob · 2013-07-22 03:09:20

please make the expression clear with brackets

eg 3^(2x+1) 0r 3^(2x) + 1

thanks

EbenezerSon · 2013-07-22 03:39:13

There is no bracket involved in it from where I copied.
It is treated under indices.
I have solved similar problem but this seems insoluble at some point.
I will solvd for you to see where I got stuck.

EbenezerSon · 2013-07-22 04:02:28

Here I go.

(3^x)^2 * 3 - 3^x*3^2 - 3^x*3 +1=0

Let 3^x = M. therefore substitution.
3m^2 - 9m - 3m + 1

= 3m^2 - 12m + 1=0
factorization seem impossible here.

Bob · 2013-07-22 04:15:17

I just wanted to be clear that the problem is:

If so then x = -1 and -2 are not solutions:

This is not zero.

Bob

bobbym · 2013-07-22 04:17:12

Hi;

That can not be factored. You need as Bob suggests to clean the question up.

EbenezerSon · 2013-07-22 04:54:57

I have solved a similar question successfuly, see.

3^2x+3 - 4(3^x+1) + 1=0

Last edited by EbenezerSon (2013-07-22 07:30:52)

bobbym · 2013-07-22 05:00:04

Hi;

Please bracket that a little better.

EbenezerSon · 2013-07-22 05:21:06

That is how it exist in the book I am working with.

bobbym · 2013-07-22 05:22:38

What does 3^2x+3 mean?

Bob · 2013-07-22 05:31:15

I think it is unlikely that a book would use the symbol ^

please look again at post 5

Is the equation I have put there the one in your book?

Bob

EbenezerSon · 2013-07-22 06:37:09

bobbym wrote:

What does 3^2x+3 mean?

It means the 3 has raised to the power 2x+3.

bobbym · 2013-07-22 06:44:58

Hasn't he raised a good point with

bob bundy wrote:

I think it is unlikely that a book would use the symbol ^

I would agree, but you say it is there! But then his post #5 is correct and that is not a solution.

EbenezerSon · 2013-07-22 06:51:24

bobbym wrote:

Hasn't he raised a good point with
bob bundy wrote:
I think it is unlikely that a book would use the symbol ^
I would agree, but you say it is there! But then his post #5 is correct and that is not a solution.

The book did not use the symbol ^, I rather used it , because the 2x +3 is at the top of the 3 in the book.

bobbym · 2013-07-22 06:58:21

Hi;

This is exactly what is in the book then?

EbenezerSon · 2013-07-22 07:00:19

bob bundy wrote:

I just wanted to be clear that the problem is:
If so then x = -1 and -2 are not solutions:
This is not zero.
Bob

Yes that's how it is arranged, in the book.

Last edited by EbenezerSon (2013-07-22 07:03:09)

EbenezerSon · 2013-07-22 07:01:28

bobbym wrote:

Hi;
This is exactly what is in the book then?

Yes Sir!. Positive 1 is at the end

Last edited by EbenezerSon (2013-07-22 07:03:46)

bobbym · 2013-07-22 07:04:42

It is obviously some sort of typo.

EbenezerSon · 2013-07-22 07:09:34

bobbym wrote:

It is obviously some sort of typo.

The book is before me now and has positive 1 just at the end.

Last edited by EbenezerSon (2013-07-22 08:25:55)

bobbym · 2013-07-22 07:35:04

It still looks like a mistake in the book. -1 and -2 are not roots of that equation.

EbenezerSon · 2013-07-22 07:45:58

Then please how exactly would the final answer be?

bobbym · 2013-07-22 07:53:41

I could not solve that by hand. It takes a computer to solve it. The answer involves complex numbers further showing that the problem is mistyped.

EbenezerSon · 2013-07-22 08:53:08

Yeb I must believe you, c'os the author stated explicitly that, a student should forgive any mistake that would be found in the book. Is just at the beginning of the book .
:-) But still you're darling!

Last edited by EbenezerSon (2013-07-22 08:53:35)

bobbym · 2013-07-22 08:55:23

If you are marked wrong about it then you will have the consolation of knowing that I would have been marked wrong too.

Bob · 2013-07-22 09:50:40

So now the question has become:

It still will not lead to those answers:

x = -1

x = -2

Closest equation with those answers that I can find:

Bob

Math Is Fun Forum

#1 2013-07-22 03:02:49

Find the truth set of the following.

#2 2013-07-22 03:09:20

Re: Find the truth set of the following.

#3 2013-07-22 03:39:13

Re: Find the truth set of the following.

#4 2013-07-22 04:02:28

Re: Find the truth set of the following.

#5 2013-07-22 04:15:17

Re: Find the truth set of the following.

#6 2013-07-22 04:17:12

Re: Find the truth set of the following.

#7 2013-07-22 04:54:57

Re: Find the truth set of the following.

#8 2013-07-22 05:00:04

Re: Find the truth set of the following.

#9 2013-07-22 05:21:06

Re: Find the truth set of the following.

#10 2013-07-22 05:22:38

Re: Find the truth set of the following.

#11 2013-07-22 05:31:15

Re: Find the truth set of the following.

#12 2013-07-22 06:37:09

Re: Find the truth set of the following.

#13 2013-07-22 06:44:58

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#14 2013-07-22 06:51:24

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#15 2013-07-22 06:58:21

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#16 2013-07-22 07:00:19

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#17 2013-07-22 07:01:28

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#18 2013-07-22 07:04:42

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#19 2013-07-22 07:09:34

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#20 2013-07-22 07:35:04

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#21 2013-07-22 07:45:58

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#22 2013-07-22 07:53:41

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#23 2013-07-22 08:53:08

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#24 2013-07-22 08:55:23

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#25 2013-07-22 09:50:40

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