√12+2√35=√(√5+√7)2=∣∣√5+√7∣∣=√5+√7

Vania is scared of bunjee jumping

1.A

2.B

3.C

4.A

5.D

Điều kiện xác định:x ≥1 

\(\sqrt{9x+9}+\sqrt{x+1}=20\)

⇔\(9\sqrt{x+1}+\sqrt{x+1}=20\)

⇔\(10\sqrt{x+1}=20\)

⇔\(\sqrt{x+1}=\dfrac{20}{10}\)

⇔\(\sqrt{x+1}=2\)

⇔\(\left(\sqrt{X+1}\right)^2=2^2\)

⇔\(x+1=4\)

⇔\(x=3\left(nhận\right)\)

1.cook

2.help

3.lived

4.was

5.have

6.read

1.D

2.D

3.C

4.B

5.A

6.C

7.D

8.B

1.A

2.D

3.C

4.A

5.C

6.B

7.C

8.B

không chắc đúng

1.finishes

2.do-eat

3.they are singing

4.spending

5.has

6.is

7.am going

8.is - doing- is practicing

9.are- studying

10.watches

11.Are- writting

.