All-reversible multi-step reaction

Each reaction j has its standard potential and the Nernst equation is, as in Eq. 4.15, 

Dependin9 on which current approximation we use for 9, each one is a linear wei9hted sum of c. and one (2-point) or more c. points at x 0. 

Making use of the recursive relations 4.47,. .., the left-hand side of Eq. 4.50 can be written in terms of only c q and the equation written as 

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