Therefore, . In other words, is one of the roots of the resolvent cubic ("") and this suggests that the roots of that cubic are equal to , , and . This is indeed true and it follows from Vieta's formulas. It also follows from Vieta's formulas, together with the fact that we are working with a depressed quartic, that . (Of course, this also follows from the fact that .) Therefore, if , , and are the roots of the resolvent cubic, then the numbers , , , and are such that