View Full Version : Logarithms to the Base 10
LynnM
Sep 1, 2010, 10:50 AM
Can anyone explain how [log_{b}x^{2}] / [log100] simplifies to log_{b}x? Please and thank you!
Unknown008
Sep 1, 2010, 10:39 PM
That's simple... :) look here:
\frac{log_b x^2}{log\ 100}
You know that 100 = 10^2, so:
\frac{log_b x^2}{log\ 100} = \frac{log_b x^2}{log\ 10^2}
\frac{log_b x^2}{log\ 100} = \frac{2log_b x}{2 log\ 10}
Recall that log_a a = 1
\frac{2log_b x}{2 log\ 10} = log_b x
LynnM
Sep 2, 2010, 12:14 PM
Oh, that really is simple! Thanks! What seems to be not-so-simple is LaTeX. I attempted to use it but it didn't show up in the same format as yours. This is what I typed: \frac{log_{b}x^{2}}{log100}. Did I go wrong somewhere? It worked in the practice box.
Unknown008
Sep 3, 2010, 08:42 AM
Yes, it is good. You only need the 'math' tabs now.
That is, you put [/math] and but in the reverse order. I can't put it in the correct order or everything between those tabs get into LaTeX format. If you can't understand, just press on 'Quote User' in my post above, or in this one:
[math]Test
If you have one character to make subscript, or superscript, the { and } are not necessary. For example,
\log_b gives log_b
log_10 gives log_10
log_{10} gives log_{10}
One last thing, if you have simple fractions, that is numerical one digit numerator and one digit denominator,
\frac12 gives \frac12
but
\frac1 23 gives \frac1 23
LynnM
Sep 3, 2010, 09:07 AM
That stuff is so neat! I will give it a try again. I'm pretty sure I understand what you mean about the reverse order! Let's see... \frac45. Hmm, it doesn't change when I click preview.:confused: Perhaps I have to submit it first. I'll give that a try... fingers crossed!
LynnM
Sep 3, 2010, 09:08 AM
Yay! Thanks! (I'm really quite excited about this!)