Huong is a student in class 7A at Quang Trung school. Collecting glass bottles is one of her favorite hobbies. She started her hobby when she was 10 years old. She often shares her/ the hobby with her sister. She finds her hobby interesting and useful. She feels happy when she looks at beautiful flower vases made from them. She will continue her hobby in the future because it helps save the environment.

MK CHÚC BẠN HỌC TỐT NHA

Chia động từ:

a) Lan (be).was.......... tired yesterday.

b) He (live)..lives......... with his grandparents in Ho Chi Minh City.

c) ..Do..... you (live)..live...... in an apartment?

BANJ TICK CHO MK NHA

Trong thí nghiệm Y–âng về giao thoa ánh sáng với nguồn sáng đơn sắc, hệ vân trên màn có khoảng vân là i. Nếu tăng khoảng cách hai khe thêm 6% và giảm khoảng cách từ hai khe đến màn bớt đi 4% so với ban đầu thì khoảng vân giao thoa trên màn

A. giảm 9%

B. giảm 2%

C. giảm 9,44%

D. giảm 10%

Tìm x:

9,5 x x = 399

\(\frac{1}{a-1}=\left(1-\frac{1}{b-1}\right)+\left(1-\frac{1}{c-1}\right)=\frac{b-2}{b-1}+\frac{c-2}{c-1}\ge2\sqrt{\frac{\left(b-2\right)\left(c-2\right)}{\left(b-1\right)\left(c-1\right)}}\)

Tương tự với \(\frac{1}{b-1};\text{ }\frac{1}{c-1}\)

Rồi nhân theo vế 3 bất đẳng thức: 

\(\frac{1}{\left(a-1\right)\left(b-1\right)\left(c-1\right)}\ge8\sqrt{\frac{\left(a-2\right)^2\left(b-2\right)^2\left(c-2\right)^2}{\left(a-1\right)^2\left(b-1\right)^2\left(c-1\right)^2}}=8\frac{\left(a-2\right)\left(b-2\right)\left(c-2\right)}{\left(a-1\right)\left(b-1\right)\left(c-1\right)}\)

\(\Rightarrow\left(a-2\right)\left(b-2\right)\left(c-2\right)\le\frac{1}{8}\)

Vậy GTLN của H là 0,125.

Đẳng thức xảy ra khi \(a=b=c=\frac{5}{2}.\)

1) complete the sentences , using the present perfect of the words in the box and either SINCE or FOR :

enioy , grow , learn , live , make , know , move , not see , sleep , win

1. I ....have seen...................my sister .........since.............January

2. we .........have lived.................here..for.......................a long time , but we're going to move soon

3. the world.....has enjoyed.................Beethoven's music.......for...............nearly 200 years

4. Tam ......has lept..................in the upstairs bedroom.......since..................................he shared it with his brother

5. ........for...................the last five years , we....have moved..........................our home twice

6. our soccer team ....has won................all games.....since..................the beginning of the season

7. we can speak a little english now because we ....have learn...............english .......for..............three years

8. little Ben ,......has grown...............................a lot .....since..............we saw him last time

9. as a student , i .have made....................many mist6akes ......since...........i started school

10 . how long ..have...........you .....know...........your best friend ? -.........since.................................i was a kid of five

DÙ MK LÀM SAU NHƯNG MK XIN BẠN HÃY TICK CHO MK, PLEASE

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