Số phần số quả táo mẹ cho chị là \(\dfrac{1}{4}=\dfrac{5}{20}\) ( số quả táo )

Số phần số quả táo mẹ cho em là \(\dfrac{2}{5}=\dfrac{8}{20}\) ( số quả táo )

Vì \(\dfrac{8}{20}>\dfrac{5}{20}\) nên \(\dfrac{2}{5}>\dfrac{1}{4}\) 

Vậy em được mẹ cho nhiều táo hơn

42. They must be at the sports ground now. They usually _____________ basketball on Fridays.
A. play B. are playing
C. have played D. have been playing
43. I _____________ my work already. I’m ready to go for a walk with you.
A. finish B. am finishing
C. have finished D. have been finishing
44. I _____________ breakfast right now. Can you call a tittle later?
A. cook B. am cooking
C. have cooked D. have been cooking
45. I _____________this book. Can I borrow it for a week or so?
A. don’t read B. am not reading
C. haven’t read D. haven’t been reading
46. Maria is good at languages. She _____________ French, Spanish and German.
A. speaks B. is speaking
C. has spoken D. has been speaking
47. So far, he _____________ five stories for children.
A. writes B. is writing
C. has written D. has writing
48. We _____________ for their answer for two months already
A. wait B. are waiting
C. have been waited D. have been waiting
49. She _____________ since Monday.
A. is sick B. is being sick
C. has been sick D. has been being sick
50. She _____________ since noon. Should we wake her up?
A. sleeps B. is sleeping
C. has been sleep D. has been sleeping

3. Rewrite the sentences which make no change in their meanings

11. He doesn’t open the book.

The book isn't opened by him

12. People speak English in almost every corner of the world.

English is spoken in almost evvery corner of the world

13. Nothing can change my mind.

My mind can't be changed

14. I heard her sing this song last night.

She was heard to sing this song last night

15. She helps me to do all these difficult exercises.

I am helped to do all the these difficult exercises by her

9. surface 

Nữa chu vi hcn là \(468:2=234\left(m\right)\)

Chiều dài hcn là \(\left(234+38\right):2=136\left(m\right)\)

Chiều rộng hcn là \(136-38=98\left(m\right)\)

Diện tích hcn là \(136.98=13328\left(m\right)\)

1. B

2. B

3. C

4. C

5. B

6. A

7. C

8. D

9. A

10. A

3. education

4. pollution

5. unanswered

6. saving

7. Unluckily

8. beside

9. faced

10. authorized

Áp dụng hệ thức liên quan tới đường cao vào △vuông ABC ta được

\(AH^2=HB.HC\Rightarrow AH=\sqrt{HB.HC}=\sqrt{225.64}=120\)

a. \(Q=\left(\dfrac{\sqrt{x}}{\sqrt{x}+1}-\dfrac{1}{x+\sqrt{x}}\right)\left(\dfrac{1}{\sqrt{x}+1}+\dfrac{2}{x-1}\right)\)

\(=\dfrac{x-1}{\sqrt{x}\left(\sqrt{x}+1\right)}.\dfrac{\sqrt{x}+1}{x-1}=\dfrac{1}{\sqrt{x}}\)

b. Ta có \(x=3+2\sqrt{2}\Rightarrow\sqrt{x}=\sqrt{3+2\sqrt{2}}=\sqrt{\left(\sqrt{2}+1\right)^2}=\sqrt{2}+1\)

Thay \(\sqrt{x}=\sqrt{2}+1\) vào \(Q\), ta được

\(Q=\dfrac{1}{\sqrt{2}+1}\)

c. \(Q< 0\Leftrightarrow\dfrac{1}{\sqrt{x}}< 0\) mà \(1>0\Rightarrow\sqrt{x}< 0\) ( vô lý )

Vậy không có x thỏa ycbt