221k views
3 votes
Logx - logx-1^2=2log(x-1)

2 Answers

3 votes

Answer:

x is approximately 2.220744

Explanation:

This can be simplified a little using properties of logarithms, and then solve it by graphing:


log(x)-log(x-1)^2=2\,log(x-1)\\log(x)-2\,log(x-1)=2\,log(x-1)\\log(x)=4\,log(x-1)

So we use a graphing tool to find the intersection point of the graph of
log(x), and the graph of
4\,log(x-1)

Please see attached image for the graph and solution.

The value of x is approximately 2.220744

Logx - logx-1^2=2log(x-1)-example-1
User Akenion
by
5.3k points
2 votes

Answer:

x = 2.32011574011

Explanation:

The problem with your original equation is that it is a long way of saying ...

log(x) -log(x) -1 = 2log(x-1)

0 -1 = 2log(x-1)

which has the solution ...

-1/2 = log(x -1)

1/√10 = x -1

x = 1 + 1/√10 ≈ 1.3162278

__

We have asked for clarification, and what we got was ...


\log{(x)}-\log{(x-1^2)}=2\log{(x-1)}

which, again, is a long way of saying ...


\log{(x)}-\log{(x-1)}=2\log{(x-1)}

The other reasonable interpretation of your 'clarified' equation is ...


\log{(x)}-\log{((x-1)^2)}=2\log{(x-1)}

which you already have an answer to. You have declared that a "misconception."

So, we are left with the interpretation that the equation you want a solution to is ...


\log{(x)}-\log{(x-1)}=2\log{(x-1)}

_____

When solving these graphically, I like to write the equation as a function whose zero(s) we're trying to find. For this, when we subtract the right side, we get ...


f(x)=\log{(x)}-3\log{(x-1)}

A graphing calculator shows that f(x) = 0 when ...

x ≈ 2.32011574011

__

If you don't like my interpretation, check out the second attachment. It has your x-1² as the argument of the middle term. You can see that the calculator interpreted that the same way I did (as required by the order of operations).

Logx - logx-1^2=2log(x-1)-example-1
Logx - logx-1^2=2log(x-1)-example-2
User Enver Arslan
by
5.3k points
Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.