# Meaning of # and & in a RootSum expression [closed]

I'm working on calculating the first passage time in a continuous time Markov process. To do this, I have to solve a system of 10 coupled differential equations using DSolve, and I plan to integrate one of the solutions to get my final answer.

Here is the problem I'm having. DSolve accurately calculates the answer but it displays it using RootSum with symbols #1 and &. Here is the beginning and end of the solution:

RootSum[
3628800 B^9 + A^8 #1 + 12 A^7 B #1 + 116 A^6 B^2 #1 +
(...)
2352 A B #1^6 + 8862 B^2 #1^6 + 64 A #1^7 + 432 B #1^7 + 9 #1^8) &]


Where A and B are symbols for arbitrary rational numbers.

I've read in the documentation that the # is used as a placeholder for an element of a list following the &, which would come at the end of the solution. However, in this case there is no list after the &, so I'm not sure what to make of it.

## closed as off-topic by Daniel Lichtblau, m_goldberg, bbgodfrey, Edmund, MarcoBJul 22 '17 at 3:20

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "This question arises due to a simple mistake such as a trivial syntax error, incorrect capitalization, spelling mistake, or other typographical error and is unlikely to help any future visitors, or else it is easily found in the documentation." – Daniel Lichtblau, m_goldberg, bbgodfrey, Edmund, MarcoB
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