Nghĩa của các từ láy sau đây là gì?Đặt câu với mỗi từ láy đó:

a/bập bềnh

b/nheo nhéo

b

Tìm a,b,c biết:

a/\(\dfrac{a}{2}=\dfrac{b}{3}=\dfrac{c}{5}\)và a.b.c=810

b/\(\dfrac{a}{4}=\dfrac{b}{3}=\dfrac{c}{9}\)và \(a-3b+4c=62\)

c/\(\dfrac{2a}{3}=\dfrac{3b}{4}=\dfrac{4c}{5}\)và a+b+c=49

d/\(\dfrac{a}{b}=\dfrac{9}{7}\)và\(\dfrac{b}{c}=\dfrac{7}{3}\),a-b+c=15

Cho tỉ lệ thức:\(\dfrac{a}{b}=\dfrac{c}{d}.\)CMR:\(\dfrac{2a+3b}{2a-3b}=\dfrac{2c+3d}{2c-3d}\)

Tìm \(x\in Z\),biết:

a/\(x^2=16\)

b/\(x^3=-8\)

c/\(\left(x+2\right)^2=4\)

d/\(\left(1-x\right)^3=1\)

e/\(\dfrac{1}{4}.\dfrac{1}{6}.\dfrac{3}{8}.\dfrac{4}{10}.....\dfrac{14}{30}.\dfrac{15}{32}=2^x\)

Tính:

a/\(4^{11}:2^{10}:2^{11}\)

b/\(\dfrac{11.2^{11}-10.4^5}{16^3}\)

c/\(\left(2^5+14.2^4\right):2^3\)

d/\(A=12.\left(-\dfrac{2}{3}\right)^2+\dfrac{4}{3}\)

Combine the sentences,using relative clause.

1.Jack is reading the novel.I don't like this novel.

_...............................................................................................................................................................................

2.The girls are performing the play.You met their parents 3 days ago.

-...................................................................................................................................................................................

3.Their parents are anxious about their children.The children come back late.

-................................................................................................................................................................................

4.The lecturer is my uncle.He gave an interesting talk on TV last night.

-................................................................................................................................................................................

5.There's a woman living next door.She is a doctor.

-The woman.............................................................................................................................................................

6.I've got a brother called Jim.He lives in London.He's a engineer.

-My brother Jim.......................................................................................................................................................

7.Laura painted a picture,and it's being shownn in an exhibition.

-The picture.............................................................................................................................................................

8.The house is empty now.I used to live there.

-The house...............................................................................................................................................................

9.We're looking forward to a concert.It's next Saturday.

-The concert.............................................................................................................................................................

10.Jane doesn't know anything about the city.Her sister is working in that city.

Jane..........................................................................................................................................................................

11.The students have become quiet proficient in their new languges.They attend class five hours per day.

-................................................................................................................................................................................

12.Disney World is a famous amusement park.It's located in orlando,Florida,USA,and covers a large area of land.

-................................................................................................................................................................................

13.Sunlight wakes me up early in the morning.It comes through the window.

-...........................................................................

14.The radio has suddenly stopped working.It is not very old.

.......................................................................................................

15.The people were very nice.We visited them yesterday.

...............................................................................................................................................................................

16.The girl decided to travel by train.She is afraid of airplanes.

.................................................................................................................................................................................

17.i like listening to music.Music can help me relax after a hard working day.

.................................................................................................................................................................................

18.Whales and dolphins both make sounds.These sounds are sinilar to a languges.

.................................................................................................................................................................................

19.A woman spoke to me.She was very helpful.

.................................................................................................................................................................................

20.The girl sits next to me.She is my close friend.

.................................................................................................................................................................................

Chiếu một tia sáng SI đến gương phẳng và hợp với mặt gương một góc 45⁰.Quay gương quanh trục trùng với mặt gương qua I một góc 5 độ.Góc giửa tia tới là bai nhiêu độ?