\(a,\Leftrightarrow\Delta=\left(m+3\right)^2-4m^2=0\\ \Leftrightarrow\left(m+3-2m\right)\left(m+3+2m\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}3-m=0\\3m+3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}m=3\\m=-1\end{matrix}\right.\\ b,\Leftrightarrow\Delta=36\left(m-1\right)^2-4\left(2m-3\right)\left(m-1\right)=0\\ \Leftrightarrow36m^2-72m+36-8m^2+20m-12=0\\ \Leftrightarrow28m^2-52m+24=0\\ \Leftrightarrow7m^2-13m+6=0\\ \Leftrightarrow\left[{}\begin{matrix}m=1\\m=\dfrac{6}{7}\end{matrix}\right.\\ c,\Leftrightarrow\Delta=\left(2-m\right)^2+4\left(m-1\right)=0\\ \Leftrightarrow m^2-4m+4+4m-4=0\\ \Leftrightarrow m^2=0\Leftrightarrow m=0\)

\(A1+2=A2\)

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