Êâàäðàòíîå óðàâíåíèå è ïðèëîæåíèÿ òåîðåìû Âèåòà.
1.
Ñóììà êîðíåé êâàäðàòíîãî óðàâíåíèÿ x2+ (ê2 + 4ê - 5 )õ
– ê = 0 ðàâíà íóëþ ïðè ê, ðàâíîì:
2.
 êâàäðàòíîì óðàâíåíèè (à2 – 5à + 3 )x2 + (3à - 1)õ + 2 = 0 îäèí êîðåíü
â äâà ðàçà áîëüøå äðóãîãî, åñëè à ðàâíî:
3.
Ñóììà êâàäðàòîâ âñåõ êîðíåé óðàâíåíèÿ x2 + 3÷õ÷ + 1 = 0 ðàâíà:
4.
Ñóììà êîðíåé óðàâíåíèÿ x2 – 2à( õ – 1 ) – 1 = 0 ðàâíà
ñóììå êâàäðàòîâ åãî êîðíåé, åñëè à ðàâíî:
5.
Ñóììà êóáîâ êîðíåé óðàâíåíèÿ 3x2 + 2õ – 3 = 0 ðàâíà: