# Anyone want to try their hand at a nonlinear simultaneous set of equations?

#### Capn

##### Platinum Member
It's the off-season and my brain is in storage till september.

Anyway, so somebody did a best fit to some data using the equation form of

eta = [C1*x1 + C2*(x2^C3)]^(-1)

So I don't have the values for C1..C3, but need to find them out, but I do have more than three data points with x1, x2, and eta.

Pt 1
eta = 0.322294
X1 = 5.0
X2 = 10.0

Pt 2
eta = 0.123184
X1 = 5.0
X2 = 100.0

Pt 3
eta = 0.001896
X1 = 5.0
X2 = 1000.0

I'm not that great at solving the nonlinear equations anyways, but I'll try again just want somebody to double check my values maybe. This isn't a class assignment or anything.

#### LouisXIX

##### Senior member
use a graphical calculator!

#### DAM

##### Diamond Member
x1 = eta^-1 - c2(x2^c3)/c1

x2 = root of c3(eta^-1 - c1*x1/c2)

dam()

edit

ohh crap i just notice a mistake in the above give me a couple of minutes and ill solve them for ya.

dam()

/edit

#### LouisXIX

##### Senior member
psstt, dam, use logarithms

#### DAM

##### Diamond Member
actually all you have to do is solve for both then plug them back into the other equation, or use maple or mathematica to solve the equation for all possible solutions.

dam()

#### Capn

##### Platinum Member
I didn't have maple available to me when i was at work, but now I can telnet in to my school and use it.

#### DAM

##### Diamond Member
wait but i though it the question was &quot;how many roads must a man walk?&quot;

dam(HHGTTG)