Bestimme in Q [ 7 ] {\displaystyle {}\mathbb {Q} [{\sqrt {7}}]} das Inverse von 2 + 5 7 {\displaystyle {}2+5{\sqrt {7}}} .
![{\displaystyle {}\mathbb {Q} [{\sqrt {7}}]}](https://wikimedia.org/api/rest_v1/media/math/render/svg/a180d901c00fed3f947629a858193942ea844fd5)
das Inverse von 
.
