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31 tháng 10 2021

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

Dấu '=' xảy ra khi x=5

12 tháng 3 2022

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(x)=2x^3-2x^3+x^2+3x^2-4x^2-3x+5x+1=-3x+6

b: P(0)=-3*0+6=6

P(-1)=6+3=9

P(1/3)=-1+6=5

c: P(x)=0

=>-3x+6=0

=>-3x=-6

=>x=2

P(x)=1

=>-3x+6=1

=>-3x=-5

=>x=5/3

 

22 tháng 1 2022

used to deliver

used to be

used to go

used to drive

used to spend

used to believe

used to work

used to serve

22 tháng 1 2022

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

18 tháng 6 2023

5T

6F

7T

8F

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18 tháng 6 2023

F - F - T - F

19 tháng 6 2023

1. Mohenjo-Daro was 4000 years old

19 tháng 6 2023

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.

25 tháng 3 2021

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

 

25 tháng 3 2021

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