Bài 1 : 

Thay x = 2 ; y = -1/2 ta được 

\(B=-8+2.4\left(-\dfrac{1}{2}\right)-4.2.\left(\dfrac{1}{4}\right)+2\left(-\dfrac{1}{2}\right)-3\)

\(=-8-4-2-1-3=-18\)

a) Ta có: \(\left(2x-3\right)\left(3x+4\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-3=0\\3x+4=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=3\\3x=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=-\dfrac{4}{3}\end{matrix}\right.\)

Vậy: \(S=\left\{\dfrac{3}{2};-\dfrac{4}{3}\right\}\)

b) Ta có: \(x^3-3x^2+3x-1=\left(x-1\right)\left(x+1\right)\)

\(\Leftrightarrow\left(x-1\right)^3-\left(x-1\right)\left(x+1\right)=0\)

\(\Leftrightarrow\left(x-1\right)\left[x^2-2x+1-x-1\right]=0\)

\(\Leftrightarrow\left(x-1\right)\left(x^2-3x\right)=0\)

\(\Leftrightarrow x\left(x-1\right)\left(x-3\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x-1=0\\x-3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=1\\x=3\end{matrix}\right.\)

Vậy: S={0;1;3}

c) Ta có: \(x^2+x=2x+2\)

\(\Leftrightarrow x\left(x+1\right)-2\left(x+1\right)=0\)

\(\Leftrightarrow\left(x+1\right)\left(x-2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x+1=0\\x-2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-1\\x=2\end{matrix}\right.\)

Vậy: S={-1;2}

d) Ta có: \(\left(x-1\right)^2=2\left(x^2-1\right)\)

\(\Leftrightarrow\left(x-1\right)^2-2\left(x-1\right)\left(x+1\right)=0\)

\(\Leftrightarrow\left(x-1\right)\left(x-1-2x-2\right)=0\)

\(\Leftrightarrow\left(x-1\right)\left(-x-3\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-1=0\\-x-3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\-x=3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=-3\end{matrix}\right.\)Vậy: S={1;-3}

e) Ta có: \(2\left(x+2\right)^2-x^3-8=0\)

\(\Leftrightarrow2\left(x+2\right)^2-\left(x^3+8\right)=0\)

\(\Leftrightarrow2\left(x+2\right)\cdot\left(x+2\right)-\left(x+2\right)\left(x^2-2x+4\right)=0\)

\(\Leftrightarrow\left(x+2\right)\left(2x+4-x^2+2x-4\right)=0\)

\(\Leftrightarrow\left(x+2\right)\cdot\left(-x^2+4x\right)=0\)

\(\Leftrightarrow-x\left(x+2\right)\left(x-4\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x+2=0\\x-4=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-2\\x=4\end{matrix}\right.\)

Vậy: S={0;-2;4}

a: \(P=-\left|5-x\right|+2019\le2019\forall x\)

Dấu '=' xảy ra khi x=5

used to deliver

used to be

used to go

used to drive

used to spend

used to believe

used to work

used to serve

1. used to deliver

2. used to be 

3. used to go

4. used to drive

5. used to spend

6. used to believe

7.used to work

8. used to serve

5T

6F

7T

8F

F - F - T - F

1. Mohenjo-Daro was one of the first city.

2. If we look at a map of Mohenjo-Daro, we can see the straight street.

3. Rome was the capital of the Roman Republic and Empire for a thousand years.

4. London was the biggest city in the world between 1831 and 1925.

5. Tokyo is the biggest city in the world now.

IV

1 to have

2 making 

3 leaving

4 seeing

5 to get

6 arguing - working

7 to have

8 to seeing

9 not touching

10 to disappoint

V

1 on - on

2 at - at

3 in - in

4 at

5 at 

6 in

7 in - in

8 at - in

9 in - at

10 in

VI

1 are - reach

2 comes

3 flies

4 have just decided - will undertake

5 would take

6 was

8 am attending - was attending

9 arrived - was waiting

10 had lived

VII

1 send - will receive

2 will - improve - do

3 will - has

4 doesn't phone - will leave

tờ 2

5 don't study - won't oas

VIII

1 had - would learn

2 told - would be

3 lived - would do

4 would help - knew

5 would buy - had

IX

1 went

2 were

3 wrote

4 could

5 bought

6 studied

7 went

8 would stop

9 were

10 lead

X

1 He opened the window in order to let fresh air in

2 I took my camera so that I could take some phôt

3 He studied really hard in order to get better marks

4 Jason learns Chinese to work in China

5 I've collected money in order that I will buy a new car

XI

1 A new museum has been built in the city center by the council

2The explosion had been caused by a bomb

3 Their flat was broken into last month

4 Jane won't be invited to his birthday party by him

5 The important decisions are made in many families

6 The date of the meeting has been changed

7 The car is going to be repaired for us by the garage next week

8 She had her car repaired yesterday

9 His watch was stolen yesterday

10 The bank manager was made hand over on the money by the robbers

11 He hasn't went abroad before

12 She has driven for 1 month

13 We have eaten since it started to rain

14 We haven't met for a long time

15 I haven't had a delicious food like this before

16 Nam said that he was told to be at school before 7 o'clock

17 Thomas said that all the students would have a meeting the week after

18 She said that her parents were very proud of her gook marks

19 The teacher said that all the homework had to be done carefully