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1,
a) 3,2x +(-12)x +2,7=-4,9 b)-5,6x+2,9x-3,86=-9,8
=>3,2x+(-12)x=-4,9-2,7 =>-5,6x+2,9x=-9,8+3,86
=>3,2x+(-12)x=-7,6 =>-5,6x+2,9x=-5,94
=>x[3,2+(-12)]=-7,6 =>x[(-5,6)+2,9]=-5,94
=>2x=-7,6=>x=-7,6:2=-3,8 =>-2,7x=-5,94=>x=(-5,94):(-2,7)=2,2
tiếp nè các bạn
I. chọn từ có cách phát âm khác nhau với những từ khác (từ in đậm)
a. calculator b. marble c. famous d. erase
a. event b. bell c. relax d. essay
a. bluff b. club c. fun d. junior
a. indoors b. school c. hoop d. shoot
a. equation b. education c. invitation d. dictionarry
II. tìm từ sai sau đó sửa lại (in đậm )
1. to make=>making
2. of=>in
3.start usually=>usually start
4. good=>well
5. in=>at
tiếp nè các bạn
I. chọn từ có cách phát âm khác nhau với những từ khác (từ in đậm)
a. calculator b. marble c. famous d. erase
a. event b. bell c. relax d. essay
a. bluff b. club c. fun d. junior
a. indoors b. school c. hoop d. shoot
a. equation b. education c. invitation d. dictionary
II
1. this=>the
2. of=>in
3. start usually=> usually start
4. .....
5. in=>at
Choose the words or phrases that are not correct in Standard English.
1. There are=> is a large, modernBmodernB bathroom andCandC a kitchen inDinD the apartment.
2. He thanks her about=> for BaboutB invitting himChimC toDtoD the party.
1.There are large,modern bathroom and a kitchen in the apartment
Lỗi sai:are chữa lại:is
2.Mình chịu
giúp mình với
I. choose one word that has the same meaning as the word in capitals
1. REPAIR a. enjoy b. fix c. play d. help
2. LEARN a. study b. like c. write d. read
3. COMMON a. free b. noisy c. different d. popular
4. RIGHT a. famous b. left c. correct d. nice
5. DIFFICULT a. easy b. hard c. energetic d. favorite
II. chọn từ sai sau đó sủa lại cho đúng dưới từ gạch chân (mình cho in đậm nha)
1. The student do=>is doing some experimentsB atC the momentD.
2. what do you usually do at=>in your free time ?
3. you should practice speak=>to speak English before you go to England
4. Never=>eitheir they read or study at the same time.
5. She is very good of =>at writing essays
I. choose one word that has the same meaning as the word in capitals
1. REPAIR a. enjoy b. fix c. play d. help
2. LEARN a. study b. like c. write d. read
3. COMMON a. free b. noisy c. different d. popular
4. RIGHT a. famous b. left c. correct d. nice
5. DIFFICULT a. easy b. hard c. energetic d. favorite
II. chọn từ sai sau đó sủa lại cho đúng dưới từ gạch chân (mình cho in đậm nha)
1. The student do => are doing some experiments at the moment
2. what do you usually do at => in your free time ?
3. you should practice speak => speaking English before you go to England
4. Never they read or => and study at the same time.
5. She is very good of => at writing essays
tham khảo Tìm phân số a/b bằng phân số 18/27 , biết rằng ƯCLN - Online Math
Error Identification.
1.JeanJean cloth waswas made completecomplete=>completely fromfrom cotton.
2.WouldWould you like comecome=>to come and visitvisit me nextnext summer?
3.Ao Dai waswas frequentlyfrequently worn by both manman=>men and womenwomen.
4.Wearing uniformsWearing uniforms helphelp=>helps students feelfeel equal in many waysways.
5.WearingWearing uniforms encouragesencourages students to be to be proud aboutabout =>of their school.
6.She wisheswishes she cancan =>could speak English as wellwell asas her teacher.
7.I seldom gogo to aa football match.I'm not very interestinginteresting=>interested inin football.
8.A newnew style of jeans havehave=>has just been introducedintroduced in in the USA.
9.InIn the 18th18thcentury, jean cloth waswas made completelycompletely byby=>from cotton.
10.Mr.Brown is interestedinterested in to go shopping to go shopping=>going shopping everyevery Sunday.
11.I wishwish I havehave=>had a new watch. MineMine is too too old.
12.Emma used toused to lie onon the beach when she liveslives=>lived by the seaby the sea.
13.WearingWearing uniforms encourageencourage=>encourages the students to beto be proud of theirtheir schools.
14.How longlong havehave you learninglearning=>learnt EnglishEnglish?
15.Ao dai waswas frequentfrequent=>frequently worn worn by both men and womenboth men and women.
Error Identification.
1.Jean cloth was made complete=>completely from cotton.
2.Would you like come=>to come and visit me next summer?
3.Ao Dai was frequently worn by both man=>men and women.
4.Wearing uniforms help=>helps students feel equal in many ways.
5.Wearing uniforms encourages students to be proud about =>of their school.
6.She wishes she can =>could speak English as well as her teacher.
7.I seldom go to a football match.I'm not very interesting=>interested in football.
8.A new style of jeans have=>has just been introduced in the USA.
9.In the 18th century, jean cloth was made completely by=>from cotton.
10.Mr.Brown is interested in to go shopping=>going shopping every Sunday.
11.I wish I have=>had a new watch. Mine is too old.
12.Emma used to lie on the beach when she lives=>lived by the sea.
13.Wearing uniforms encourage=>encourages the students to be proud of their schools.
14.How long have you learning=>learnt English?
15.Ao dai was frequent=>frequently worn by both men and women.
ta có :
\(\dfrac{bz-cy}{a}=\dfrac{cx-az}{b}=\dfrac{ay-bx}{c}=\dfrac{bxz-cyz}{ax}=\dfrac{cxy-azy}{by}=\dfrac{ayz-bxz}{cz}\)áp dụng tính chất dãy tỉ số bằng nhau, ta có:\(\dfrac{bzx-cyx}{ax}=\dfrac{cxy-azy}{by}=\dfrac{ayz-bxz}{cz}=\dfrac{bzx-cyx+cxy-azy+ayz-bxz}{ax+by+cz}=0\)
suy ra : bz-cy=0 \(\Rightarrow bz=cy\Rightarrow\dfrac{y}{b}=\dfrac{z}{c}\left(1\right)\)
cx-az=0\(\Rightarrow cx=az\Rightarrow\dfrac{x}{a}=\dfrac{z}{c}\left(2\right)\)
ay-bx=0\(\Rightarrow ay=bx\Rightarrow\dfrac{x}{a}=\dfrac{y}{b}\left(3\right)\)
từ (1), (2) và (3) suy ra: \(\dfrac{x}{a}=\dfrac{y}{b}=\dfrac{z}{c}\)
Ta có: \(\dfrac{bz-cy}{a}\)= \(\dfrac{cx-az}{b}\)=\(\dfrac{ay-bx}{c}\)
\(\Rightarrow\dfrac{abz-acy}{a^2}=\dfrac{bcx-baz}{b^2}=\dfrac{cay-cbx}{c^2}\)(nhân cả tử và mẫu với mẫu của phân số)
\(=\dfrac{abz-acy+bcx-baz+cay-cbx}{a^2+b^2+c^2}\) (t/c của dãy tỉ số bằng nhau)
(đến đây ta thấy tử = 0 vì chúng là các số đối nhau, abz-baz; acy-cay; bcx-cbx)
\(=\dfrac{0}{a^2+b^2+c^2}\)
\(\Rightarrow\)\(\dfrac{bz-cy}{a}\)= 0 (mà để là một phân số thì mẫu phải khác 0) suy ra a khác 0 vậy bz-cy=0 \(\Rightarrow bz=cy\Rightarrow\dfrac{z}{c}=\dfrac{y}{b}\)(1)
tương tự \(\dfrac{cx-az}{b}\)=0 suy ra \(\dfrac{x}{a}=\dfrac{z}{c}\) từ 1 và 2 suy ra điều phải c/m\(\)