Solution at two equal eigenvalues

If equal eigenvalues result in a Vandermond determinant, which equals zero, eq. (2.53) can no longer be solved with respect to p,. With 

Differentiation by an order of s - 1 changes the matrix V only in the column k and k. These two can be represented by 

For this reason the simple consecutive reaction discussed in Example 2.22 results in 

General solutions are possible if the two eigenvalues are formally combined by a variable A. This general solution is inserted for the intermediate B in Example 2.22  

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