(i) A + 1/B = 2
(ii) B + C*A = 9.7(iii) C + A/B = 5.14
by inspection B cannot equal 0
from (i)
(iv) A = 2  1/B
from (ii)
(v) B = 9.7  C*A
from (iii)
(vi) C= 5.14  A/B
substitute (iv) into (v)
(vii) B = 9.7  C*(2  1/B)
Substitute (iv) into (vi)
(viii) C = 5.14  (2  1/B)/B
Substitute (viii) into (vii)
(ix) B = 9.7  (5.14  (2  1/B))*(2  1/B)
Multiply both sides by B^3 and rearrange
(x) B^4 + .58B^3  9.14B^2 + 4B 1 = 0
This quartic has one rational solution: B=2.5
(I used my trusty graphing calculator)
There is another real around 3.52 and complex approximately .22 +/ .25i (I used WolframAlpha)
Solution A=1.6, B=2.5, C=4.5

Posted by Jer
on 20161119 22:39:14 