Simplify the following:

EbenezerSon · 2014-09-27 09:01:30

Then that would be decimal numbers I think.

bobbym · 2014-09-27 09:02:06

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

EbenezerSon · 2014-09-28 04:47:59

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)

bobbym · 2014-09-28 07:50:48

Hi;

I am getting 1 / 4 as well.

EbenezerSon · 2014-09-28 23:39:52

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

bobbym · 2014-09-28 23:41:09

First algebraically clean it up a bit.

EbenezerSon · 2014-09-28 23:49:30

Like this?

x - x^4 = 8^2

bobbym · 2014-09-28 23:55:52

logx - 4logx = 2

EbenezerSon · 2014-09-29 01:00:19

bobbym wrote:

logx - 4logx = 2

wierd to me though

bobbym · 2014-09-29 01:09:05

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.

EbenezerSon · 2014-09-29 01:12:45

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?]

bobbym · 2014-09-29 01:21:04

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

EbenezerSon · 2014-09-29 01:42:13

bobbym wrote:

logx - 4logx = 2

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

bobbym · 2014-09-29 01:48:23

Divide both sides by -3.

EbenezerSon · 2014-09-30 02:37:21

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

bobbym · 2014-09-30 04:09:16

Yes, that is the reason tjhey were invented for.

EbenezerSon · 2014-09-30 04:42:51

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?

bobbym · 2014-09-30 04:52:49

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

EbenezerSon · 2014-10-01 04:55:46

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)

bobbym · 2014-10-01 06:06:34

That is written

EbenezerSon · 2014-10-01 21:03:38

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)

bobbym · 2014-10-01 21:15:04

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

EbenezerSon · 2014-10-04 06:20:26

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.

bobbym · 2014-10-04 06:23:33

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

EbenezerSon · 2014-10-04 06:31:13

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

Thank you very much

Math Is Fun Forum

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

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

Re: Simplify the following:

Board footer