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21 tháng 9 2021

1 A

2 C

3 D

4 A

5 D

6 D

7 A

8 B

9 C

10 D

11 A

12 C

13 B

14 D

15 B

23 tháng 3 2022

Em cảm ơn ạ

2 tháng 10 2021

\(A1+2=A2\)

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

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

2 tháng 10 2021

Thanksss bann nhiều lắm nhoa

27 tháng 9 2021

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

9 tháng 10 2021

a) \(A=x^4+4x+7=\left(x^2+4x+4\right)+3=\left(x+2\right)^2+3\ge3\)

\(minA=3\Leftrightarrow x=-2\)

b) \(B=x^2-x+1=\left(x^2-x+\dfrac{1}{4}\right)+\dfrac{3}{4}=\left(x-\dfrac{1}{2}\right)^2+\dfrac{3}{4}\ge\dfrac{3}{4}\)

\(minB=\dfrac{3}{4}\Leftrightarrow x=\dfrac{1}{2}\)

c) \(C=4x-x^2+3=-\left(x^2-4x+4\right)+7=-\left(x-2\right)^2+7\le7\)

\(maxC=7\Leftrightarrow x=2\)

d) \(D=2x-2x^2-5=-2\left(x^2-x+\dfrac{1}{4}\right)-\dfrac{9}{2}=-2\left(x-\dfrac{1}{2}\right)^2-\dfrac{9}{2}\le-\dfrac{9}{2}\)

\(maxD=-\dfrac{9}{2}\Leftrightarrow x=\dfrac{1}{2}\)

16 tháng 8 2021

1 D

2 C

3 D

4 C

5 B

6 D

7 A

8 A

9 B

10 D

11 C

12 B

12 tháng 8 2021

a)Hóa trị 4

b)Ba hóa trị 2

a) Mn hóa trị IV

b) Ba hóa trị II

10 tháng 11 2021

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