| Line 8: | Line 8: | ||
-- | -- | ||
| − | As stated above: <math>\sqrt[3]{4}=(\sqrt[3]{2})^2</math>, so [Q(<math>\sqrt[3]{2}+sqrt[3]{4}</math>:Q]=3. This means we need a polynomial of degree 3. You can use the same process as 14 by letting x=<math>\sqrt[3]{2}+sqrt[3]{4}</math> then find <math> | + | As stated above: <math>\sqrt[3]{4}=(\sqrt[3]{2})^2</math>, so [Q(<math>\sqrt[3]{2}+ \sqrt[3]{4} </math>):Q]=3. This means we need a polynomial of degree 3. You can use the same process as 14 by letting x=<math>\sqrt[3]{2}+\sqrt[3]{4}</math> then find <math>x^3</math> which I found to equal 6x-6. (I found it easier to refer to <math>\sqrt[3]{2}+\sqrt[3]{4}</math> as 2^(1/3) and 2^(2/3) when doing the calculations.) |
| − | I think this is right as the polynomial has <math>\sqrt[3]{2}+sqrt[3]{4}</math> as a zero. Did anyone else get this? | + | I think this is right as the polynomial has <math>\sqrt[3]{2}+\sqrt[3]{4}</math> as a zero. Did anyone else get this? |
Revision as of 14:48, 3 December 2008
Following the same procedures as with a square root does not get me anywhere. Does anyone have any suggetions? on how to find the minimal polynomial for a cube root?! --Robertsr 23:49, 2 December 2008 (UTC)
Yea, I keep trying to solve this in a similar way as 14 but it doesn't work. Grrr.
Remember that $ \sqrt[3]{4}=(\sqrt[3]{2})^2 $ so $ \sqrt[3]{4} $ is the only important one
--
As stated above: $ \sqrt[3]{4}=(\sqrt[3]{2})^2 $, so [Q($ \sqrt[3]{2}+ \sqrt[3]{4} $):Q]=3. This means we need a polynomial of degree 3. You can use the same process as 14 by letting x=$ \sqrt[3]{2}+\sqrt[3]{4} $ then find $ x^3 $ which I found to equal 6x-6. (I found it easier to refer to $ \sqrt[3]{2}+\sqrt[3]{4} $ as 2^(1/3) and 2^(2/3) when doing the calculations.) I think this is right as the polynomial has $ \sqrt[3]{2}+\sqrt[3]{4} $ as a zero. Did anyone else get this?
