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Trả lời:
1/ Gọi số bông hoa của ba học sinh A;B;C lần lượt là a; b; c ( bông hoa; \(a;b;c\inℕ^∗\) )
Theo bài ra, ta có:
\(a:b:c=2:3:4=\frac{a}{2}=\frac{b}{3}=\frac{c}{4}\) và ( a + c ) - b = 6
Áp dụng tc dãy tỉ số bằng nhau, ta có:
\(\frac{a}{2}=\frac{b}{3}=\frac{c}{4}=\frac{\left(a+c\right)-b}{\left(2+4\right)-3}=\frac{6}{3}=2\)
\(\Rightarrow\hept{\begin{cases}a=4\\b=6\\c=8\end{cases}}\) ( tm )
Vậy số bông hoa của 3 bạn A; B; C lần lượt là: 4 bông; 6 bông; 8 bông
2/ Gọi chiều rộng và chiều dài của HCN lần lượt là x và y ( cm; x và y > 0 )
Theo bài ra, ta có:
\(x:y=4:7\Rightarrow\frac{x}{4}=\frac{y}{7}\) và xy = 112
Đặt \(\frac{x}{4}=\frac{y}{7}=k\left(k\ne0\right)\)
\(\Rightarrow\hept{\begin{cases}x=4k\\y=7k\end{cases}}\)
Ta có: xy = 112
=> 4k.7k = 112
=> 28k2 = 112
=> k2 = 4
=> k = 2 hoặc k = - 2
+) Với k = 2 ta có: \(\hept{\begin{cases}x=4k=4.2=8\\y=7k=7.2=14\end{cases}}\) ( tm )
+) Với k = - 2, ta có: \(\hept{\begin{cases}x=4k=4\left(-2\right)=-8\\y=7k=7\left(-2\right)=-14\end{cases}}\) ( không tm )
Vậy chu vi hình chữ nhật là: 2 ( x + y ) = 2 ( 8 + 14 ) = 44 ( cm )
Trả lời:
1, Ta có: \(x+y=\frac{1}{2};y+z=\frac{1}{3};z+x=\frac{1}{4}\)
\(\Rightarrow x+y+y+z+z+x=\frac{1}{2}+\frac{1}{3}+\frac{1}{4}\)
\(\Rightarrow2x+2y+2z=\frac{13}{12}\)
\(\Rightarrow2\left(x+y+z\right)=\frac{13}{12}\)
\(\Rightarrow x+y+z=\frac{13}{24}\)
\(\Rightarrow\hept{\begin{cases}x=\frac{13}{24}-\frac{1}{3}=\frac{5}{24}\\y=\frac{13}{24}-\frac{1}{4}=\frac{7}{24}\\z=\frac{13}{24}-\frac{1}{2}=\frac{1}{24}\end{cases}}\)
2, Ta có: \(x:y:z=3:5:\left(-2\right)\Rightarrow\frac{x}{3}=\frac{y}{5}=\frac{z}{-2}\)
Áp dụng tc dãy tỉ số bằng nhau, ta có:
\(\frac{x}{3}=\frac{y}{5}=\frac{z}{-2}=\frac{5x-y+3z}{5.3-5+3.\left(-2\right)}=\frac{124}{4}=31\)
\(\Rightarrow\hept{\begin{cases}x=93\\y=155\\z=-62\end{cases}}\)
3, Ta có: \(2x=3y\Rightarrow\frac{x}{3}=\frac{y}{2}\Rightarrow\frac{x}{21}=\frac{y}{14}\left(1\right)\)
\(5y=7z\Rightarrow\frac{y}{7}=\frac{z}{5}\Rightarrow\frac{y}{14}=\frac{z}{10}\left(2\right)\)
Từ (1) và (2) => \(\frac{x}{21}=\frac{y}{14}=\frac{z}{10}\)
Áp dụng tc dãy tỉ số bằng nhau, ta có:
\(\frac{x}{21}=\frac{y}{14}=\frac{z}{10}=\frac{3x-7y+5x}{3.21-7.14+5.10}=\frac{30}{15}=2\)
\(\Rightarrow\hept{\begin{cases}x=42\\y=28\\z=20\end{cases}}\)
31. He is sure to have an accident because he drives very ........careless............. CARE
32. One of them is ...........walking...............for fun WALK
33. After the .........invention...........of equipment, man could swim freely underwater INVENT
34. He is a famous football..............player............... PLAY
35. Peter can solve problems................wisely.......................... WISE
41. Where’s the ……nearest…… post office from here, Tam ? Near
42. Hoa has a pen pal from France and they write to each other……regularly…… . regular
43. There are four ……musicians……… in that pop music. Music
44. I have ……less…… time to play than my friend. little
45. We take part in many different ……activities…… at recess. ac
II. Choose from the four options given C marked A, B, C or D one best answer to complete each sentence by choosing the corresponding letter A, B, C or D.
11. Playing chess after dinner sounds...................................to me
A. boring B. bored C. boringly D. boredom
12. They sat and watched the black and white programs ...................
A. all the evening B. all of the evening C. all evening D. all of evening
13. People of................can take part in the walking activity
A. every age B. each age C. all ages D. all the ages
14. Peter can drive a car and ......................his sister Mary
A. too can B. can also C. so can D. can so
15. That boy is better..................history than I am
A. for B. with C. at D. in
16. Lien never eats durians because she doesn’t lik.e their.................
A. smell B. smelly C. smells D. smelled
17. People in Asia often drink................................
A. some tea B. the tea C. tea D. many tea
18. I don’t want much sugar in my coffee. Just.........., please
A. few B. little C. a little D. a few
19. If he eats all that food, he eats............................
A. too much B. too many C. quite much D. quite many
20. Do you often help your parents...........................the housework?
A. with B. about C. for D. at
21. Please .............. the milk carefully. I don’t want to boil over.
A. see B. watch C. look at D. noe
22. “Was he disappointed ?” – “Yes, he found the movie .................”
A. boring B. boringly C. bors D. bored
23. ............ 20 September, 1529, five small ship set sail from Spain.
A. at B. in C. on D. by
24. Every student in those five rooms must bring .............. own book to class.
A. one’s B. his C. their D. someone’s
25. “Was the competition a success ?” “Yes, ............ people took part in it more than usual”.
A. more B. fewer C. less D. many
26. Lien never eats durians because she doesn’t their .................. .
A. smell B. smelly C. smells D. smelling
27. Some people are used to ................ in crowded streets and don’t mind it at all.
A. riding B. ride C. rides D. is riding
28. She can not skate board, and I can’t ....................... .
A. too B. neither C. either D. so
29 . When I was a boy, I ................... tea to coffee.
A. prefer B. preferred C. prefers D. prefering
30. Every girl ought to learn ................... to look.
A. what B. when C. how D. where
Đáp án
Old furniture is sold by the man at the end of the street
Học tốt
Old furniture is sold at the end of the street by the man.
1-C.Floor
2-B.ill
3-D.Pretty
4-A.Apparent
5-C.Clear
6-D.souvenir
7-B.wear
8-A.Type
9-C.Teenager
10-D
11-D
12-B
13-C
#H
Question V- Fill one suitable word in each gap to complete the following passage. Identify your answer by writing the corresponding word or phrase on your answer paper.
1: one
2:for
3:has
4:knows
5:players
6:them
7:begins
8:on
9:season
10:train
Question VI. Read the following passage and choose the best answer A, B, C or D to fill the blanks
In the United States of America, the national language is …...(1)......... English. Four hundred years ago, some English people came to North America to live and they brought ......(2)....... language to this country.
Now in the USA, people speak.........(3).......English . Most of the words are the……(4)..…in American and British English, but the American say some English words not as people speak in England. Canada is …..(5)..... to the North of the United States of America. It is larger ....(6)...... the United States. In Canada, many people …..(7)...... English because they also came from England many years ........(8).... But in some parts of Canada, people speak French because they came from France.
1. A. also B. C. as D. not
2. A. French B. English C. Chinese D. Canadian
3. A. British B. American C. Russian D. Chinese
4. A. various B. similar C. same D.
5. A. lies B. situated C. at D. in
6. A. than B. as C. more D. less
7. A. say B. tell C. talk D. speak
8. A. ago B. later C. there D. here
Ps : nhớ k :33
# Aeri #
Câu 1: Gọi số học sinh mỗi khối \(7,8,9\)lần lượt là \(x,y,z\)học sinh \(x,y,z\inℕ^∗\).
Vì mỗi học sinh khối \(7,8,9\)trồng được theo thứ tự là \(2,3,4\)cây và số cây mỗi khối trồng được bằng nhau nên
\(2x=3y=4z\Leftrightarrow\frac{x}{6}=\frac{y}{4}=\frac{z}{3}\)
Áp dụng tính chất dãy tỉ số bằng nhau ta được:
\(\frac{x}{6}=\frac{y}{4}=\frac{z}{3}=\frac{x+y+z}{6+4+3}=\frac{130}{13}=10\)
\(\Leftrightarrow\hept{\begin{cases}x=10.6=60\\y=10.4=40\\z=10.3=30\end{cases}}\)(tm)
Câu 2:
Có \(s=vt\)nên \(v\)và \(t\)là hai đại lượng tỉ lệ nghịch.
Vận tốc ô tô tăng lên \(20\%\)thì thời gian thực tế bằng số phần thời gian dự định đi trên nửa quãng đường đó là:
\(1\div\left(1+20\%\right)=\frac{5}{6}\)
Thời gian dự định đi nửa quãng đường là:
\(10\div\left(6-5\right)\times6=60\)(phút)
Thời gian thưc tế ô tô đi từ A đến B là:
\(60\times2-10=130\)(phút)