help:solve nonlinear equation
 

學校裡的老師出了一題要解vapor-liquid-equilibrium(VLE)的flash
裡面有用到7條方程式解7各未知數
想請教大大....要如何解啊:cry:

題目

parameter:
p1sat=3236.324045
p2sat=1586.897953
p=3169.60812
a12=718.2261
a21=1270.4458
z1=0.5
z2=0.5


k1=r1*p1sat/p............(1)
k2=r2*p2sat/p............(2)
x1=z1/((1-v)+k1*v).....(3)
x2=z2/((1-v)+k2*v).....(6)
ln(r1)=-ln(x1+x2*a12)-x2*(-a12/(x1+x2*a12)+a21/(x1*a21+x2))...(5)
ln(r2)=-ln(x2+x1*a21)-x1*(a12/(x1+x2*a12)-a21/(x1*a21+x2)).....(6)
x1+x2=1................(7)

solve x1,x2,k1,k2,v,r1,r2

推推...希望會的大大肯賜教一下:)