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3 tháng 8 2021

D

2 You should say you are sorry

3 He ought ask his teacher about it

4 You should start having lessons

5 She ought not to watch TV late

6 You should get some exercise

E

1 can

2 could

3 ought

4 can

5 should

6 couldn't

7 can't

8 ought to

9 can

10 can

F

1 - D

2 - C

3 - B

4 - E

5 - A

 

 

2 You should say you are sorry

3 He ought ask his teacher about it

4 You should start having lessons

5 She ought not to watch TV late

6 You should get some exercise

5 tháng 2 2021

g, PT \(\Leftrightarrow\dfrac{x+24}{1996}+1+\dfrac{x+25}{1995}+1+\dfrac{x+26}{1994}+1+\dfrac{x+27}{1993}+1+\dfrac{x+2036}{4}-4=0\)

\(\Leftrightarrow\left(x+2020\right)\left(\dfrac{1}{1996}+\dfrac{1}{1995}+\dfrac{1}{1994}+\dfrac{1}{1993}+\dfrac{1}{4}\right)=0\)

\(\Leftrightarrow x+2020=0\)

\(\Leftrightarrow x=-2020\)

Vậy ...

Bài 3: 

1: =>2x=-5/3-1/2=-10/6-3/6=-13/6

hay x=-13/12

2: =>3/5x=1/7+3/5=5/35+21/35=26/35

hay x=26/3

3: =>-3x=5/6+3/4=10/12+9/12=19/12

hay x=-19/36

4: =>1/2x=3/7-5/4=12/28-35/28=-23/28

hay x=-23/14

5: =>1/4x=-3/5-7/5=-2

hay x=-8

6: =>3x=1/42+1/7=1/42+6/42=1/7

hay x=1/21

21 tháng 2 2022

bạn có chắc đúng ko ạ

25 tháng 2 2021

I)1.B

2.B

3.C

4.D

5.C

II)

1.B

2.D

3.B

4.B

5.A

6.B

7.tell....way.

8.C

III)

1.isn't teaching

2.drive

3.has

 

16 tháng 8 2021

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16 tháng 8 2021

\(x^2+2x+1=x^2+2\cdot1x+1^2=\left(x+1\right)^2\)

\(4x^2+12x+9=\left(2x\right)^2+2\cdot3\cdot2x+3^2=\left(2x+3\right)^2\)

\(\dfrac{4}{9}a^2-\dfrac{4}{3}a+1=\left(\dfrac{2}{3}a\right)^2-2\cdot\dfrac{2}{3}\cdot1a+1^2=\left(\dfrac{2}{3}a-1\right)^2\)

\(a^2+5a+\dfrac{25}{4}=a^2+2\cdot2,5a+2,5^2=\left(2,5+a\right)^2\)

9 tháng 8 2021

Bài 1:

a) (2x+5)(x-6)=2x2+5x-12x-30=2x2-7x-30

b) (2x-1)(x2-4x+3)=2x3-8x2+6x-x2+4x-3=2x3-9x2+10x-3

c) x2-2x-(x-7)(x+2)=x2-2x-x2+7x-2x+14=3x+14

d) 3x-(x+2)(x+4)=3x-x2-2x-4x-8=-x2-3x-8

9 tháng 8 2021

Bài 2:

a) 2(x+1)=x-1

⇒2x+2=x-1

⇒2x+2-x+1=0

⇒x+3=0

⇒x=-3

b) x(x+2)-x2=1

⇒x2+2x-x2=1

⇒2x=1

⇒x=0,5

c) 3x(x-2)=(3x-1)(x-1)-5

⇒3x2-6x=3x2-x-3x+1-5

⇒3x2-6x-3x2+x+3x-1+5=0

⇒-2x+4=0

⇒-2x=-4

⇒x=2

d) 6(x-1)(x-2)-6x(x+3)=2x

⇒6(x2-x-2x+2)-6x2-18x-2x=0

⇒6x2-6x-12x+12-6x2-18x-2x=0

⇒-38x+12=0

⇒-38x=-12

⇒x=\(\dfrac{6}{19}\)

a:ta có: \(2x^2\ge0\)

\(\Leftrightarrow2x^2+1>0\forall x\)

vậy: H(x) vô nghiệm