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tamanh nguyen
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Lấp La Lấp Lánh
6 tháng 10 2021 lúc 21:17

Hình 1:

Áp dụng tslg:

\(cosK=\dfrac{IK}{MK}\)\(\Rightarrow cos42^0=\dfrac{12}{y}\Rightarrow y\approx16,15\)

\(tanK=\dfrac{IM}{IK}\Rightarrow tan42^0=\dfrac{x}{12}\Rightarrow x\approx10,8\)

Hình 2:

\(sinG=\dfrac{HT}{GT}\Rightarrow sin35^0=\dfrac{y}{16}\Rightarrow y\approx9,18\)

\(cosG=\dfrac{GH}{GT}\Rightarrow cos35^0=\dfrac{x}{16}\Rightarrow x\approx10,11\)

 

Nguyễn Lê Phước Thịnh
6 tháng 10 2021 lúc 21:19

Hình 1:

\(x=12\cdot\tan42^0\simeq10.8\left(cm\right)\)

\(y=\sqrt{10.8^2+12^2}\simeq16,14\left(cm\right)\)

Lấp La Lấp Lánh
6 tháng 10 2021 lúc 23:25

Hình 3:

\(sinF=\dfrac{UP}{PF}\Rightarrow sin55^0=\dfrac{16}{y}\Rightarrow y\approx19,53\)

\(tanF=\dfrac{UP}{UF}\Rightarrow tan55^0=\dfrac{16}{x}\Rightarrow x\approx11,2\)

Khánh Trương Văn
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Ngân Lê Bảo
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Đỗ Thanh Hải
11 tháng 7 2021 lúc 22:23

1 Mary asked me who I talked to when i had problems

2 Hoa said she would help her mum cook dinner that night

3 jack advised me to tell my teacher what had happened

4 Nam said his best friend hadn't called him for one week

5 Lucia's mother asked her if she was at the sports center then

6 Tom asked mark what time he had come home the night before

7 Mrs Brown told me not to go to the park when it gets dark

8 Mrs QUang told Trung they had spoken to his parents the day before

9 Minh asked Phuong if he could meet her at 4.30 the day after afternoom

10 Nga said she was staying with her aunt and uncle in the suburbs

Hoàng Hạnh Nguyễn
11 tháng 7 2021 lúc 22:24

1. Mary asked me who I talked to when I had problems.

2. Hoa said that she would help her mum cook dinner that night.

3. Jack advised me to tell my teacher what had happened.

4. Nam said that his best friend hadn't called him for one week.

5. Lucia's mother asked her if she were at the sports centre then.

6. Tom asked Mark what time he had come home the previous night.

7. Mrs. Brown told me not to go to the park when it got dark.

8. Mr. Quang said to Trung that they had spoken to his parents the day before.

9. Minh asked Phuong if he could met her at 4.30 that next afternoon.

10. Nga said that she was staying with her aunt and uncle in the suburbs.

Trần Văn Dương
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๖ۣۜDũ๖ۣۜN๖ۣۜG
27 tháng 4 2022 lúc 16:30

Câu 3:

a) 

CTPT xủa X là CnH2n+2O

\(n_{CO_2}=\dfrac{8,96}{22,4}=0,4\left(mol\right)\Rightarrow n_{C_nH_{2n+2}O}=\dfrac{0,4}{n}\left(mol\right)\)

=> \(n_{H_2O}=\dfrac{\dfrac{0,4}{n}.\left(2n+2\right)}{2}=\dfrac{0,4}{n}\left(n+1\right)\left(mol\right)\)

Mà \(n_{H_2O}=\dfrac{9}{18}=0,5\left(mol\right)\)

=> n = 4

=> CTPT: C4H10O

b) \(n_{C_4H_{10}O}=\dfrac{0,4}{4}=0,1\left(mol\right)\)

=> m = 0,1.74 = 7,4 (g)

c)

(1) \(CH_3-CH_2-CH_2-CH_2OH\)

(2) \(CH_3-CH_2-CH\left(OH\right)-CH_3\)

(3) \(CH_3-C\left(CH_3\right)\left(OH\right)-CH_3\)

(4) \(CH_3-CH\left(CH_3\right)-CH_2OH\)

(5) \(CH_3-CH_2-CH_2-O-CH_3\)

(6) \(CH_3-CH\left(CH_3\right)-O-CH_3\)

(7) \(CH_3-CH_2-O-CH_2-CH_3\)

d)

X là \(CH_3-C\left(CH_3\right)\left(OH\right)-CH_3\) (2-metylpropan-2-ol)

Ngân Lê Bảo
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𝓓𝓾𝔂 𝓐𝓷𝓱
3 tháng 7 2021 lúc 21:57

1) \(A=\dfrac{x+2+x-\sqrt{x}-x-\sqrt{x}-1}{x\sqrt{x}-1}:\dfrac{\sqrt{x}-1}{5}\)

        \(=\dfrac{\left(\sqrt{x}-1\right)^2}{\left(\sqrt{x}-1\right)\left(x+\sqrt{x}+1\right)}\cdot\dfrac{5}{\sqrt{x}-1}\) \(=\dfrac{5}{x+\sqrt{x}+1}\)

2) Ta thấy \(x+\sqrt{x}+1=\sqrt{x}\left(\sqrt{x}+1\right)+1>1\forall x\)

\(\Rightarrow A< 5\)

 

Kim Anhh
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Thảo Phương
20 tháng 8 2021 lúc 13:14

1/ \(n_S=\dfrac{6,4}{32}=0,2;n_{H_2SO_4}=\dfrac{14.70\%}{98}=0,1\)

Bảo toàn nguyên tố S : \(n_S=n_{H_2SO_4\left(lt\right)}=0,2\)

Mà thực tế chỉ thu được 0,1

=> \(H=\dfrac{0,1}{0,2}.100=50\%\)

Thảo Phương
20 tháng 8 2021 lúc 13:17

2/ \(n_{N_2}=0,2\left(mol\right);n_{H_2}=0,3\left(mol\right);n_{NH_3}=0,15\left(mol\right)\)

PTHH: \(N_2+3H_2\rightarrow2NH_3\)

Lập tỉ lệ : \(\dfrac{0,2}{1}>\dfrac{0,3}{3}\)=> Sau phản ứng N2 dư, tính theo số mol H2

=> n NH3(lt)= \(\dfrac{0,3.2}{3}=0,2\left(mol\right)\)

Mà thực tế chỉ thu được 0,15 mol 

=> \(H=\dfrac{0,15}{0,2}.100=75\%\)

Phạm Khánh Hà
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Hienlinh Phan
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Linh
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Linh
24 tháng 5 2020 lúc 22:09

Luyện tập tổng hợp

Minh Nguyệt
24 tháng 5 2020 lúc 22:45

IV,

1. No, it wasn't

2. Two French brothers, Louis and Auguste Lumie

3. In the 1927

4. Because of the arrival of television in 1950s

V,

1. Why were the girls very happy?

2. Who are working in the field now ?

3. How long has Mary learned English ?

4. It was not until 2.30 that someone could leave the stadium

5. It was not until the age of 24 that Mary stopped learning Germen

6. It was not until their parents came home that they cleaned their house

Đinh Lê Bảo Vi
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