Maths Question?

[Enchanted]

(salam)

Please can someone be nice and show me how to solve this question. I really don't get logs..

Make x the subject in this equation.

ln2 + 0.5ln(x) + 0.5ln((s*x)/t) = r

Thank you.

[Invoker]

to which topic ur question relates? calculus or trigonometry?

[Enchanted]

Calculus

[repenter-gone4awhile]

ln2 + 0.5ln(x) + 0.5ln((s*x)/t) = r

ln2 + 1/2 * (ln(x) + ln((s*x)) = r

ln 2 + 1/2 * ln((x * s * x) / t) = r

2ln2 + ln((sx^2)/t) = 2r

ln4 + ln((sx^2)/t) = 2r

ln ((4sx^2)/t) = 2r

ln x^2 + ln ((4s)/t) = 2r

x^2 = e^(2r - ln ((4s)/t))

x = root(e^(2r - ln ((4s)/t)))

I think, its been 10 years since i did logarithms, so give me a break, but its something like that......i probably did a booboo somewhere....just double check it.

[Invoker]

I m not sure if its the right answer. take a look at here. u might get some help http://www.webmath.com/_answer.php

[repenter-gone4awhile]

I m not sure if its the right answer. take a look at here. u might get some help http://www.webmath.com/_answer.php

Well find out where its wrong, as i said, i probably did some boo boo.

Simple rules i remember is:

1. ln(x * y) = ln(x) + ln(y)

2. ln(x^2) = 2 * ln(x)

3. e^y = x, hence ln(x) = y

I just used these...should be somewhat right.

[Seyedeh]

http://www.wolframalpha.com/input/?i=ln2+%2B+0.5ln%28x%29+%2B+0.5ln%28%28s*x%29%2Ft%29+%3D+r+

[repenter-gone4awhile]

Looks like my answer was pretty close to the solution, if not the same thing if you split it up more.

[The Green Knight]

Calculus? *Starts getting flashbacks* Nooooo! My eyesss!!! :(

[Hot hot]

Ahh this logs and derivatives.

[Enchanted]

Thank you so much everyone. Someone wrote the correct solution and sent it to me.

Thank you for writing the rules down Repenter. I last did logs 4 years ago, so you know your logs pretty well after 10 years..