получается делаем так:
сначала решаем уравнение как и обычно т.е. теоремой виетта или дискриминантом
х^2-4х+3=0
я решу теоремой виетта:
сумма корней равна 4
произведение 3
значит корни 1 и 3
далее:
есть такая формула разложение на множетели квадратного уравнения выглядит так: a(x-x1)(x-x2), где а-множетель перед квадратом в нашем случае это 1, х1 и х2 - корни.
подставим в неё наши корни, получим (x-1)(x-3)=0
так а теперь решим это неравенство (x-1)(x-3)> 0
методом интегралов ( тут 3 промежутка от минус бесконечности до 1 от 1 до 3 и от 3 до плюс бесконечности):
допустим х =0, подставим (0-1)(0-3)=3 знак + значит в промежутке от минус бесконечности до 1 знак +
от 1 до 3 знак -
от 3 до плюс бесконечности +
ответ: х принадлежит промежутку от минус бесконечности до 1 и от 3 до плюс бесконечности
1 he taught history at school
he didn't teach history at school
did he teach history at school?
2 they left home at 8 o'clock
they did not leave home at 8 o'clock
did they leave home at 8 o'clock?
3 he stood in very good hotels
he didn't stay in very good hotels
did he stay in very good hotels?
4 you drank a lot of tea
you didn't drink a lot of tea
did you drink a lot of tea?
5 l looked tired
l didn't look tired
did l look tired?
6 we stopped in LONDON
WE DIDN'T STOP IN LONDON
DID WE STOP IN Londn?
7 pam BOUGHT A LOT OF CLOTHES
PAM DIDN'T BUY A LOT OF CLOTHES
DID PAM BYU A LOT OF CLOTHES?
8 birds flEW AWAY TO THEIR COUNTRIES
BIRDS DIDN'T FLY AWAY TO THEIR COUNTRIES
DID BIRDS FLY TO THEIR COUNTRIES?
