# got stuck in equation

Dave Angel d at davea.name
Tue Jan 1 17:42:28 CET 2013

```On 01/01/2013 11:03 AM, Chris Angelico wrote:
> On Wed, Jan 2, 2013 at 2:40 AM,  <usamazohad at gmail.com> wrote:
>> hi . . my name is usama khan
>> i am the student of civil engeering  and we got assignment to make a project program on flexible pavement design using python.
>>
>> i know very litle about programing. still learning from tutorials. u can call me a beginner.
>> now i need to solve this equation so that i can put this in python but the formula of design is very complex
>>
>> Formula is :
>>
>> log(W18) = (Z)(S)+9.36log(SN+1) -2.0+(log(dpsi/(4.5-1.5))(/(.40+1094/(SN+1)^2.5)+2.32log(Mr-)-8.07
>>
>> every thing is constant except this SN. . i want to seperate SN like SN= rest of the stuff. how can i seprate it because manualy its impossible to take SN out.
>> so plz help me out
> This isn't a Python question, it's an algebra one. I don't know what
> Z, S, and so on are, but for the most part, the basic rule of solving
> equations applies: Do the same thing to both sides and it's still
> true. Work on it until you can isolate SN on one side.

Such a rule may not be able to solve an equation when there SN appears
more than once on the RHS, and where it's inside a transcental
function.  I don't consider this an algebra problem, but a programming
problem.

> I don't know what this bit means, though:
>
> 2.32log(Mr-)
>
> Is this a transcription error? You can't subtract nullness from something.
>
> ChrisA

Mr-   was apparently intended to mean "M sub r",  the subgrade resilient
modulus
<http://classes.engr.oregonstate.edu/cce/winter2012/ce492/Modules/04_design_parameters/04-2_body.htm#mr> (in
psi).  Just a number.

The only thing i know about any of this is from here:

http://classes.engr.oregonstate.edu/cce/winter2012/ce492/Modules/06_structural_design/06-3_body.htm

--

DaveA

```