As long as the one positive payment follows all of the negative payments, I guarantee that you only have one positive real root. See Re^2: Internal Rate of Return for proof. (I have the signs the other way there, but it is easy to switch them.)

Incidentally a leading payment of 0 is handled by dropping all of the payments of 0. Then either you have no payments, or you've got a leading payment that isn't 0.

In reply to Re^3: Internal Rate of Return by tilly
in thread Internal Rate of Return by ig

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