Ta có: 4a× 9b ×c = bc×ac×ab

36abc= (abc)²

36 × (abc) = ( abc)× (abc)

36=abc

=>c×c=36 (ab=c)

c²=6²

=>c = 6=>ab=6 (ab=c)

Mà bc=4a =>a= \(\frac{bc}{4}\)=>\(\frac{6b}{4}\) = \(\frac{6}{4}\)× b

=> \(\frac{6}{4}\) × b² = 6

=>b²=6: \(\frac{6}{4}\)= 6×\(\frac{4}{6}\)= 4=2²

=> b= 2

Lại có: ac=9b => a= \(\frac{9b}{6}\)=3/2 × 2=3

Vậy a=3;b=2;c=6
 

ai giúp mik vs ahihi

viết rõ ra đc k,km k hiểu?????

tớ ko mún giải . Bạn đặt \(\frac{a}{c}=\frac{c}{b}=k\)  =>  a=ck ; c=bk  và thay vào thui .  

Ta có: \(\frac{a}{c}=\frac{c}{b}\Rightarrow\left(\frac{a}{c}\right)^2=\left(\frac{c}{b}\right)^2\Rightarrow\frac{a^2}{c^2}=\frac{c^2}{b^2}=\frac{a^2+c^2}{c^2+b^2}\left(1\right)\)

Lại có: \(\left(\frac{a}{c}\right)^2=\frac{a}{c}.\frac{a}{c}=\frac{a}{c}.\frac{c}{b}=\frac{a}{b}\left(1\right)\)

Từ (1) và (2) \(\Rightarrow\frac{a^2+c^2}{c^2+b^2}=\frac{a}{b}\)

\(\Rightarrowđpcm\)

giúp mình cái mình đang cần gấp

1. competitions

2. friendship

1. competitions

2. friendship

3. performance

4. unbelieved

5. musician

6. disappeared

7. shortage

8. choice

9. religious

10. carefully

Trc khi tớ lm mong cậu đọc cho ''-.-'' : It's too long, I only did 3 sentences

1, I don’t candies either.

=> Neither do I durians

2, My sister usually plays badminton skillfully

=> My sister is usually a skillful badminton player

3, How much were these “chung” cakes?

=> What was the cost of these "chung" cake?

cảm ơn cậu^^

Ta có: \(\frac{1}{\sqrt{1}}>\frac{1}{\sqrt{100}}\)

\(\frac{1}{\sqrt{2}}>\frac{1}{\sqrt{100}}\)

\(\frac{1}{\sqrt{3}}>\frac{1}{\sqrt{100}}\)

 \(..............\)

\(\frac{1}{\sqrt{100}}=\frac{1}{\sqrt{100}}\)

\(\Rightarrow\frac{1}{\sqrt{1}}+\frac{1}{\sqrt{2}}+\frac{1}{\sqrt{3}}+...+\frac{1}{\sqrt{100}}>\frac{1}{\sqrt{100}}+\frac{1}{\sqrt{100}}+\frac{1}{\sqrt{100}}+...+\frac{1}{\sqrt{100}}\)

\(\Rightarrow>100.\frac{1}{\sqrt{100}}=10\)

\(\Rightarrowđpcm\)

Làm tắt thôi, hôm trước vừa làm câu nỳ xong, hiểu thì tự trình bày nhé~

Đặt biểu thức trên là A.Ta có:

\(\frac{1}{\sqrt{1}}>\frac{1}{\sqrt{100}}\)

\(\frac{1}{\sqrt{2}}>\frac{1}{\sqrt{100}}\)

             ...

\(\frac{1}{\sqrt{99}}>\frac{1}{\sqrt{100}}\)

\(\frac{1}{\sqrt{100}}=\frac{1}{\sqrt{100}}\)

\(\Rightarrow\frac{1}{\sqrt{1}}+\frac{1}{\sqrt{2}}+\frac{1}{\sqrt{3}}+...+\frac{1}{\sqrt{100}}>100.\frac{1}{\sqrt{100}}\)

                                                                                          \(=10\)

Vậy \(A>10\left(đpcm\right)\)

1. The old man walked..slow..................to the park. (slow, slowly, fast, fastly)

2. The man......whom.............sits next to Lan is my uncle.( who, whom, which, whose)

3. ....altthough.............it was rainy, we enjoyed our picnic very much. (But, So, Because, Although)

4. We have lived in this city......ago.................5 years( since, for, in, ago)

5. She hasn't.....ate............that kind of food before. (eat, ate, eaten, aten)

6. Your brother is studying, please ...turn off.............the TV. (turn on, turn up, turn off)

7. We should have a party to....... celebration...................this. (celebration, celebrate, decorate, decoration)

8. You watched TV late last night, .......didn't you........ jack ( do you, don't you, did you, )

.9. The novel was written .....by........Jack . (on , at, from, by)

10. The house has been built......from..............last year.(in , from, for, since) 

1. The old man walked....................to the park. (slow, slowly, fast, fastly)

2. The man...................sits next to Lan is my uncle.( who, whom, which, whose)

3. .................it was rainy, we enjoyed our picnic very much. (But, So, Because, Although)

4. We have lived in this city.......................5 years( since, for, in, ago)

5. She hasn't.................that kind of food before. (eat, ate, eaten, aten)

6. Your brother is studying, please ................the TV. (turn on, turn up, turn off)

7. We should have a party to.........................this. (celebration, celebrate, decorate, decoration)

8. You watched TV late last night, ......................?( do you, don't you, did you, didn't you)

9. The novel was written .............Jack . (on , at, from, by)

10. The house has been built....................last year.(in , from, for, since)

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