\(B=2\cdot4\cdot6\cdot8\cdot20=\left(6\cdot20\right)\cdot2\cdot4\cdot8=120\cdot2\cdot4\cdot8\)

mà 120 chia hết cho 30 (120 : 30 = 4)

=> B chia hết cho 30

Vậy B có chia hết cho 30

\(\dfrac{9^{15}.8^{11}}{3^{29}.16^8}=\dfrac{\left(3^2\right)^{15}.\left(2^3\right)^{11}}{3^{29}.\left(2^4\right)^8}=\dfrac{3^{30}.2^{33}}{3^{29}.2^{32}}\)

Ta lấy vễ trên chia vế dưới

\(=3.2=6\)

\(\dfrac{2^{11}.9^3}{3^5.16^2}=\dfrac{2^{11}.\left(3^2\right)^3}{3^5.\left(2^4\right)^2}=\dfrac{2^{11}.3^6}{3^5.2^8}\)

Ta lấy vế trên chia vế dưới

\(=2^3.3=24\)

\(\dfrac{9^{15}.8^{11}}{3^{29}.16^8}=\dfrac{\left(3^2\right)^{15}.\left(2^3\right)^{11}}{3^{29}.\left(2^4\right)^8}=\dfrac{3^{30}.2^{33}}{3^{29}.3^{32}}=3.2=6\)
\(\dfrac{2^{11}.9^3}{3^5.16^2}=\dfrac{2^{11}.\left(3^2\right)^3}{3^5.\left(2^4\right)^2}=\dfrac{2^{11}.3^6}{3^5.2^8}=2^3.3=8.3=24\)

\(\dfrac{9^{15}.8^{11}}{3^{29}.16^8}=\dfrac{3^{30}.2^{33}}{3^{29}.2^{32}}=3.2=6\)

\(\dfrac{2^{11}.9^3}{3^5.16^2}=\dfrac{2^{11}.3^6}{3^5.2^8}=2^3.3=8.3=24\)

D C D B C C C D A 

Sam puts up the decorations.

Five guests came to the party.

Molly and Sam play video games with their cousins

The family was celebrating too early. Dad's birthday was two months away.

relationship

celebration

married

golden

quietly

celebratory

refer

1. he dislike being called " the liar " => He dislike people..CALLING HIM THE LIAR.

2. The police are following the suspects => The suspects ..ARE BEING FOLLOWED BY THE POLICE.

3. She always expects to be admired by everybody => She always expects everybody..TO ADMIRE HER...

4. Someone stole his car two days ago => He had ..HIS CAR STOLEN BY SOMEONE TWO DAYS AGO..

4: Xét ΔAMC có 

I là trung điểm của AM

N là trung điểm của AC

Do đó: IN là đường trung bình của ΔAMC

Suy ra: IN//MC

hay IN//BC

1: Xét ΔABC có AB=AC

nên ΔABC cân tại A

Suy ra: \(\widehat{B}=\widehat{C}\)

Ta có: ΔBAC cân tại A

mà AH là đường trung tuyến ứng với cạnh đáy BC

nên AH là đường cao ứng với cạnh BC

1. Tam giác AOC và tam giác BOD có: AO = BO; CO = DO: góc AOC = góc BOD (đối đỉnh)

--> tam giác AOC = tam giác BOD (c.g.c)

--> góc ACO = góc ODB

Mà 2 góc này ở vị trí so le trong

--> AC // BD

b) Tam giác ACD và tam giác BDC có: CD chung; AC = BD (do tam giác AOC = tam giác BOD); góc ACO = góc ODB (câu a)

--> tam giác ACD = tam giác BDC

c) tam giác ACD = tam giác BDC (câu b)

--> góc DBC = góc CAD

Tam giác DAE và tam giác CBF có: góc DBC=góc CAD; AE = BF; BC = AD

--> tam giác DAE = tam giác CBF (c.g.c)

 1/2+1/3+1/6+1/12+1/15+1/20+1/30+1/35+1/42+1/63

=(1/2+1/6+1/12+1/20+1/30+1/42) + (1/3 +1/15+1/35+1/63)

=(1/1.2+1/2.3+1/3.4+1/4.5+1/5.6+1/6,7)+(1/1.3+1/3.5+1/5.7+1/7.9)

=(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6 -1/7) + 1/2.(2/1.3+2/3.5+2/5.7+2/7,9)

=(1-1/7)+ 1/2.(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9)

=6/7+1/2 .(1-1/9)

=6/7+1/2.(8/9)

=6/7+4/9

=82/63

học tốt

sr bạn mình làm hơi chậm nhé

82/63 nha cậu

72 : ( x - 15 ) = 8

        x - 15   = 72 : 8

        x - 15   = 9

        x          = 9 + 15

        x          = 24

Vậy x = 24 .

Học tốt !

=> x-15 = 72:8 = 9

=> x = 9+ 15 = 24

x - 15 = 72 : 8

x - 15 = 9

x = 9 + 15

x = 24

I.

1, C

2, B

3, C

4, D

5, C

6, C

7, C

8, B

bn tách ra đi, chứ nhìn qua thấy nản lắm/:

II. Choose the best answer to complete each sentence.

1.We’ll meet……………..the movies theater.           

A. in front of                  B. next to                       C. on                    D. opposite
2.Did you …….. to school yesterday.
A. go                                B. went                            C. going                D. goes.
3. It’s not far…………..here, so I often walk.
A. to                                 B. with                             C. from                 D. over
4.………………….to meet you Hoa.
A. Please                          B. Pleased                       

C. I’m please                  D. None is correct
5.Hoa is sad, because she knows …………………here.
A. someone                      B. anyone                         C. no one                   D. everyone
6.Her new school is……………than her old one.
A. bigger                          B. large                            C. beautiful                D. more
7.My brother is ………………grade 7.
A. at                                 B. in                                 C. on                          D. of
8.Everyday he………….the bus to work.
A. gives                           B. comes                          C. catches                  D. goes
9.Lan is staying…………..her aunt’s house in Hanoi now.
A. in                                 B. on                               C. with                       D. at
10.It often ……………me 15 minutes to go to school by bike.
A. takes                     B. gets                             C. gives                       D. has

11. They suggested that he…………. by bike or public transport.

A. should travel         B. might travel             C. travels                     D. traveledp

12. The light…………… so we couldn’t see any thing in the dark.

A. went                     B. went off                   C. went by                   D. went out

13. You should get a ………..to check if there is any crack in the pipe.

A. electrician             B.plumber                 C. carpenter                 D. goldsmith

14.Is it true……………. the law says there is no smoking in restaurant in this city?

A.that what                B. what                        C. if                             D. that

15. Lan is a…………………typist. She often makes many spelling mistakes.

A. careful                  B. care                      C. careless                   D.carelessly

16. Where …………. you last Sunday ?

     a. is                          b. was                    c. are                               d. were

17. Last week, Mr. Tan…………….to Ho Chi Minh City for a trip.

     a. go                         b. went                   c. going                            d. goes

18. What is your …………, Lan? – I’m 45 kilos.

     a. weight                  b. height                c. age                               d. name

19. ……………is this book? – It’s 4,000 dong.

     a. How much           b. How old            c. How many                   d. How tall

20. Yesterday, I …………….to school because I was sick.

     a. goes                     b. go                      c. went                             d. didn’t go

21. Hoa ………………her teeth three times every day.

     a. brushes                 b. brushing             c. brush                            d. brushed

22. Did you buy any souvenirs in Nha Trang ? + Yes, I ……………

     a. do                         b. am                     c. does                             d. did

23. I live ……………Quang Tri town with my grandmother.

     a. on                         b. at                        c. between                       d. in

24. ……………..did Lan go to the dentist’s last week? – Because she had a bad toothache.

     a. What                    b. Why                  c.When                            d. Where

25. Would you………….…me to the post office, please?

     a. take                      b. took                   c. taking                           d. Tak