Thread: how to find zeros of ln's

1. how to find zeros of ln's

So my problem is: f(x)= -2+ln(x^2)

I need to find the zeros of f and to figure out for what real numbers x is f defined. If anyone can explain to me how to do this I would really appreciate it. Thanks in advance!

2. Originally Posted by Jasmina8
So my problem is: f(x)= -2+ln(x^2)

I need to find the zeros of f and to figure out for what real numbers x is f defined. If anyone can explain to me how to do this I would really appreciate it. Thanks in advance!
$-2+\ln x^2 = 0 \Longleftrightarrow \ln x^2=2 \Longleftrightarrow x^2=e^2 \Longleftrightarrow |x| =e$

Tonio

3. $f(x) = 0\Rightarrow 2 = ln(x^2) \Rightarrow e^2 = e^{ln(x^2)}$

Can you finish?

Ah, I see I'm late... never mind!

4. uhh.

how do you get e^lnx^2 ?? I would really like if you can EXPLAIN to me how to get the answer. Thank you

5. Originally Posted by Jasmina8
how do you get e^lnx^2 ?? I would really like if you can EXPLAIN to me how to get the answer. Thank you

If you deal with these things you should at least know their definition, otherwise it'll be easy to fall into desperation and helplessness:

$\log_a{b}=x \Longleftrightarrow a^x=b$

Now just remember that $\ln x=\log_e{x}$

Tonio

6. .

I got it now. Thank you for your help.

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find the 0 of a ln function

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