quick log question

[Bryn]

does -log_ax = y \Longrightarrow a^{-y} = x or \Longrightarrow -a^y = x

[e(ho0n3]

-\log_a{x} = y \equiv \log_a{x} = -y

Let u = -y. Then,

\log_a{x} = u \rightarrow a^u = x \equiv a^{-y} = x

[Primarygun]

http://www.blike.com/tex/lateximg/pictures/4c5f4bf45e6be349ec73e35fa333ddd4.gif is the answer
3 y 3
log x = 3logx if that is =y , so 10 = x

How do you guys make the pictureS?

My steps can't be shown clearly

[JaKiri]

My steps can't be shown clearly

Your steps don't make sense.

And another, very similar, justification for a^-y, (using e because I can't be bothered with the subscript, but the argument's the same)

-lnx = y

lnx^-1 = y

x^-1 = e^y

x = 1/e^y

x = e^-y

[Primarygun]

It won't make sense since the forum can't show its proper format.
Therefore I want to use picture like them

[dave]

Use LaTeX code put between two [math] tags.

Take a look at the thread in general maths.

[JaKiri]

It won't make sense since the forum can't show its proper format.
Therefore I want to use picture like them

Either use latex, or display it using standard characters, like I did.

[Primarygun]

What's latex and how to get it?
Need I go to download it?

[jordan]

Take a look at the thread in general maths.
Just read the other posts, or click here. (http://www.scienceforums.net/forums/showthread.php?t=4236)

[timo]

LaTeX is like TeX (look up the latter when searching on google :P). Generally it´s a tool to write texts. It´s especially usefull for scientific texts (I don´t know a single scientist that does not write his/her texts with LaTeX/TeX) because it allows quite easy implementation of mathematical formulas, including figures, making tables and generally has a lot of features to format your text or assisting you in creating a well formatted text on your own. Firgures, chapters, subsections and formulas are numbered automatically, for example so you can insert a new formula anywhere in te text and don´t have to care about increasing the numbers of the following equations. Texts tend to also look very nice (ever wondered what scientific books are written with? -> TeX). TeX compiles your raw-text into a .pdf or .ps.
You can download it for free (dunno where - beware: My distribution was about 130MB packed). Raw-texts can be written with any ascii-editor but there are specialized editors available. I use TeXnicCenter - it´s freeware and comes close to the more famous TeXEdt.
To use TeX in this forum I think you don´t have to download anything. You can simply write TeX-code between math-tags as dave said (it´s somewhere in the FAQ, i think). If you´re an ongoing scientist or want to write good-looking essays involving formulas for school it might be a good idea to get used to TeX - most love it.

[dave]

I posted a LaTeX tutorial in General Math, which jordan has kindly linked to.

[Primarygun]

thank you