show that one fo the roots of the equation is and find the other two roots

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- Oct 15th 2008, 03:26 PMsiegfriedcubic equation help
show that one fo the roots of the equation is and find the other two roots

- Oct 15th 2008, 07:04 PMThePerfectHacker
- Oct 15th 2008, 08:24 PMsiegfried
thank you theperfecthacker

i believe you are using cardanos method but i think there is an easier method than cardanos - Oct 15th 2008, 08:30 PMThePerfectHacker
- Oct 16th 2008, 03:07 AMOpalg
Use the formulas and . These show that if then , and so . But if then . That gives the equation . The other two solutions will come from the other angles satisfying , namely and . (

**ThePerfectHacker**had , but I think must be correct.) - Oct 16th 2008, 07:25 AMThePerfectHacker