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?
The teacher should be kind and understanding. He must be able to clearly explain the new topic. On his lesson should be interesting to all students.