\(a,\Leftrightarrow\Delta=4\left(m+4\right)^2-4\left(m-4\right)\left(m-1\right)>0\\ \Leftrightarrow4m^2+32m+64-4m^2+20m+16>0\\ \Leftrightarrow52m+80>0\Leftrightarrow m>-\dfrac{20}{13}\\ b,\Leftrightarrow\Delta=\left(5m+6\right)^2-12\left(2m+3\right)\left(m+1\right)>0\\ \Leftrightarrow25m^2+60m+36-24m^2-60m-36>0\\ \Leftrightarrow m^2>0\\ \Leftrightarrow m\ne0\\ c,\Leftrightarrow\Delta=4\left(m+3\right)^2-4\left(m-5\right)\left(m-2\right)>0\\ \Leftrightarrow4m^2+24m+36-4m^2+28m-40>0\\ \Leftrightarrow52m-4>0\Leftrightarrow m>\dfrac{1}{13}\)

\(A1+2=A2\)

   \(\overline{A}\) =\(\dfrac{A1\cdot54+\cdot\left(A1+2\right)\cdot46}{100}\)=79.92

\(\Leftrightarrow\)A1=79\(\Rightarrow\)A2=81  

1 When do they do their homework?

2 Who came to the party aloe

3 Which blouse do you like

4 How did she feel after she took a nap

5 How long did she talk to him

6 How many cars do your parents have

7 When are they coming to visit you?

8 Who is your brother

9 Why don't you get up early?

10 How often do you have an English class

a)Hóa trị 4

b)Ba hóa trị 2

a) Mn hóa trị IV

b) Ba hóa trị II

Có thể giải ra lun được ko ạ 

1 had gone to bed, we watched television

2 had a swim for 5 days

3 met him for 5 months

4 gone to this club since 1999

5 come to this city since July

6 learned French since 2001

7 played chess for 3 years

8 smoked for 5 years

9 there, Jack had left the office

10 I have visited England

11 the first time I have met this lady

12 I was having dinner, the phone rang

13 we arrived there, David had left the party

14 used to wear glasses before

15 ages since we last went to a concert

16 saw her friends when she left for the United states

17 the first time I have stayed in such an expensive hotel

1 After the children had gone to bed, we watched television

2 She hasn't had a swim for 5 years

3 I haven't met him for 5 months

4 Tom hasn't gone to this club since 1999

5 They haven't come to this city since July 

6 Tom has learned French since 2001

7 She has played chess for 3 years

8 He hasn't smoked for 5 years

9 When I arrived at the office, Jack had left there

10 This is the first time I have visited England