Simple. To solve a quadratic you have to have more knowns then unknowns otherwise it is undertermined system and unresolvable.
Which is funny since Rummys known knowns were in fact mainly bull excrement his known unknows he knew were bull excrement and his unknown unknowns didn't really exist and he knew it .
So no surprise really that they got the equation so wrong and turned it into a pretty unresolvable problem .