Giúp mik câu 2 với ạ.gấp lắm ạ
Giúp e câu 3 phần đọc hiểu và câu 1 phần làm văn với ạ.Gấp ạ
Giúp em câu 1 phần tự luận vs ạ.GẤP Ạ!
1.
\(C_{12}H_{22}O_{11}+H_2O\rightarrow C_6H_{12}O_6+C_6H_{12}O_6\)
\(C_6H_{12}O_6\xrightarrow[xt:enzim]{t^o:30-35^o}2C_2H_5OH+2CO_2\)
\(C_2H_5OH+O_2\underrightarrow{xt:men\left(giấm\right)}CH_3COOH+H_2O\)
\(CH_3COOH+C_2H_5OH\underrightarrow{H_2SO_4đặc,t^o}CH_3COOC_2H_5+H_2O\)
1.
C12H22O11+H2O→C6H12O6+C6H12O6C12H22O11+H2O→C6H12O6+C6H12O6
C6H12O6to:30−35o−−−−−→xt:enzim2C2H5OH+2CO2C6H12O6→xt:enzimto:30−35o2C2H5OH+2CO2
C2H5OH+O2xt:men(giấm)−−−−−−−−−−−−→CH3COOH+H2OC2H5OH+O2xt:men(giấm)→CH3COOH+H2O
CH3COOH+C2H5OHH2SO4đặc,to−−−−−−−−−−→CH3COOC2H5+H2O
Giúp mik câu 2 với ạ gấp lắm
Câu 2.
\(\dfrac{1}{R_{tđ}}=\dfrac{1}{R_1}+\dfrac{1}{R_2}+\dfrac{1}{R_3}=\dfrac{1}{10}+\dfrac{1}{20}+\dfrac{1}{40}=\dfrac{7}{40}\)
\(\Rightarrow R_{tđ}=\dfrac{40}{7}\Omega\)
\(I_m=\dfrac{U}{R}=\dfrac{30}{\dfrac{40}{7}}=5,25A\)
\(I_1=\dfrac{U_1}{R_1}=\dfrac{30}{10}=3A\)
\(I_2=\dfrac{U_2}{R_2}=\dfrac{30}{20}=1,5A\)
\(I_3=I-I_1-I_2=5,25-3-1,5=0,75A\)
GIÚP EM BÀI 3,4,5 VỚI Ạ.GẤP Ạ..
GIÚP EM BÀI 3,4,5 VỚI Ạ.GẤP Ạ
\(B=\dfrac{x+2\sqrt{x}+3\sqrt{x}-6-9\sqrt{x}+10}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+2\right)}\\ B=\dfrac{\left(\sqrt{x}-2\right)^2}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+2\right)}=\dfrac{\sqrt{x}-2}{\sqrt{x}+2}\\ c,P=B:A=\dfrac{\sqrt{x}-2}{\sqrt{x}+2}\cdot\dfrac{\sqrt{x}-3}{\sqrt{x}-2}=\dfrac{\sqrt{x}-3}{\sqrt{x}+2}\\ P=\dfrac{\sqrt{x}+2-5}{\sqrt{x}+2}=1-\dfrac{5}{\sqrt{x}+2}\)
Ta có \(\sqrt{x}\ge0\Leftrightarrow\sqrt{x}+2\ge2\Leftrightarrow\dfrac{5}{\sqrt{x}+2}\le\dfrac{5}{2}\)
\(\Leftrightarrow P=1-\dfrac{5}{\sqrt{x}+2}\ge1-\dfrac{5}{2}=-\dfrac{3}{2}\\ P_{min}=-\dfrac{3}{2}\Leftrightarrow x=0\)
\(B=\dfrac{\sqrt{x}}{\sqrt{x}-2}+\dfrac{3}{\sqrt{x}+2}+\dfrac{9\sqrt{x}-10}{4-x}\)
\(=\dfrac{x+2\sqrt{x}+3\sqrt{x}-6-9\sqrt{x}+10}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+2\right)}=\dfrac{x-4\sqrt{x}+4}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+2\right)}=\dfrac{\left(\sqrt{x}-2\right)^2}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+2\right)}=\dfrac{\sqrt{x}-2}{\sqrt{x}+2}\)
\(P=\dfrac{B}{A}=\dfrac{\sqrt{x}-2}{\sqrt{x}+2}:\dfrac{\sqrt{x}-2}{\sqrt{x}-3}=\dfrac{\sqrt{x}-2}{\sqrt{x}+2}.\dfrac{\sqrt{x}-3}{\sqrt{x}-2}=\dfrac{\sqrt{x}-3}{\sqrt{x}+2}=1-\dfrac{5}{\sqrt{x}+2}\)
Do \(\sqrt{x}+2\ge2\Rightarrow\dfrac{5}{\sqrt{x}+2}\le\dfrac{5}{2}\Rightarrow-\dfrac{5}{\sqrt{x}+2}\ge-\dfrac{5}{2}\)
\(\Rightarrow P=1-\dfrac{5}{\sqrt{x}+2}\ge1-\dfrac{5}{2}=-\dfrac{3}{2}\)
\(minP=-\dfrac{3}{2}\Leftrightarrow x=0\)
Giúp em với ạ,em cần gấp ạ,em cám ơn ạ.GẤP LẮM RỒI Ạ
II. Give the correct form of the verbs.
1. She (leave) school a year ago.
2. James (fail) his driving test three times!
3. It’s 10 a.m. We (learn) English in our room.
4. When I came, his mother (say)said that he (just go) had just gone out.
5. The bridge (build)when I (be) there last year.
6. He (work) hard so far. I’m sure he (pass) the exam.
7. When I came, I (see) that Jakson (play) computer games while his friend (learn) English in his room.
8. I (stay) in hospital for three days last month.
9. When I (be) there last year, the bridge (build). But they (not finish) it now.
10. Yesterday, she (go) to the cinema after she (finish) her work.
11. I don’t know what’s the matter with him. He (act) funny since you (be) away.
12. He said he already (see) that man.
13. She (see) an accident while she (go) along the street.
14. All the villagers (evacuate) before the rescue workers (arrive).\
15. You (understand) verb tenses now?
III. Rewrite the sentences.
1. I arrived at the cinema, but then all the tickets had been sold.
- By the time__________________________________________
2. I rang at his lunchtime.
- When ______________________________________________
3. She phoned during my sleep.
- When_______________________________________________
4. It started to rain during my running in the park.
- When_____________________________________________
5. I played tennis and then took a bath.
- Before ____________________________________________
- After _____________________________________________
6. She started playing tennis at 6 p.m.
- She has ....................................................................................
7. They haven’t done the gardening for 6 months.
- It’s .........................................................................................
8. It took us an hour to complete the work.
- We spent .............................................................................
9. We came to the party, but then all the guests had left.
- When ..........................................................................
10. It’s the first time I have tasted this kind of seafood.
- I have ..................................................................................
IV. Choose the underlined part in each sentence (A, B,C, or D ) that needs correcting.
1. After Mrs. Wang had returned to her house from work, she was cooking dinner.
A B C D
2. I have seen lots of interesting places when I went on holiday last summer
A B C D
3. The police arrested the man while he is having dinner in a restaurant.
A B C D
4. Peter and Wendy first met in 2006, and they are married for three years.
A B C D
5. Every morning, the sun shines in my bedroom window and waking me up.
A B C D
6. What will you do when your friends won’t come?
A B C D
7. My friend didn’t drink any beer since we came to live here.
A B C D
8. We have written to each other when we were in primary school.
A B C D
V. Choose the correct sentence among A, B, C or D which has the same meaning as the given one.
1. My father hasn’t smoked cigarettes for a month.
A. It’s a month since my father last smoked cigarettes.
B. It’s a month ago that my father smoked cigarettes.
C. It’s a month that my father hasn’t smoked cigarettes.
D. It’s a cigarette that my father smoked a month ago.
2. Mr. Brown bought this car five years ago.
A. Mr. Brown started to buy this car five years ago.
B. It has been five years when Mr. Brown bought this car
C. Mr. Brown has had this car for five years .
D. It is five years ago since Mr. Brown bought this car.
3. I haven’t enjoyed myself so much for years.
A. It’s years since I enjoyed myself so much.
B. It’s years since I have enjoyed myself so much.
C. It was years since I had enjoyed myself so much.
D. It has been years since I have enjoyed myself so much.
4. The famous actor was last seen in 2000.
A. The famous actor has not been able to see since 2000.
B. No one has seen the famous actor since 2000.
C. The famous actor didn’t see anyone in 2000.
D. No one saw the famous actor until 2000.
5. I came to live here three months ago.
A. It was three months since I lived here.
B. I’ve been living here for three months.
C. I lived here for three months.
D. I didn’t live here for three months.
6. She goes to the shops every Friday.
A. She goes every day to the shop but not on Friday.
B. It’s not Friday, but she’s going to the shops.
C. She always goes to the shops on Friday.
D. She never goes to the shops on Friday.
7. Michael took a deep breath and dived into the water.
A. After Michael had taken a deep breath, he dived into the water.
B. Having taken a deep breath, he dived into the water.
C. After Michael took a deep breath, he had dived into the water.
D. A & B are correct.
8. We started working here three years ago.
A. We worked here for three years. B. We have no longer worked here for three years.
C. We have worked here for three years. D. We will work here in three years.
9. It’s a long time since we last went to the cinema.
A. We have been to the cinema for a long time. B. We haven’t been to the cinema for a long time.
C. We don’t go to the cinema as we used to. D. We wish we went to the cinema now.
10. I haven’t finished this book yet.
A. I’m still reading this book. B. I have read this book before.
C. The book I’m reading hasn’t finished. D. I will read this book some day.
11. He used to jog every morning.
A. He enjoys jogging every morning. B. He never fails to jog every morning.
C. He doesn’t now jog every morning. D. He intended to jog every morning.
12. He last had his eyes tested ten months ago.
A. He hasn’t had his eyes tested for ten months .
B. He had not tested his eyes for ten months then.
C. He had tested his eyes ten months before.
D. He didn’t have any test on his eyes in ten months.
13. Someone knocked on the door during my lunchtime.
A. I had lunch when someone knocked on the door.
B. When I had had lunch, someone knocked on the door.
C. I was having lunch when someone was knocking on the door.
D. I was having lunch when someone knocked on the door.
14. Steve left before my arrival.
A. When I arrived, Steve had already left. B. Steve left as soon as I arrived.
C. While Steve was leaving I arrived. D. Steve hadn’t left until I arrived.
15. I haven’t been here before.
A. Being here is a pleasant experience. B. This is the first time I have been here.
C. I have wished to be here for long. D. Before long I will be here.
16. The last time I saw Rose was three years ago.
A. I hasn’t seen Rose for three years. B. I haven’t seen Rose three years ago.
C. I haven’t seen Rose since three years. D. I haven’t seen Rose for three years.
17. When we arrived, the children were playing “Hide and Seek”
A. The children played “Hide and Seek” and then we arrived.
B. While the children were playing “Hide and Seek”, we arrived.
C. We arrived at the same time the children played “Hide and Seek”.
D. We didn’t arrive until the children played “Hide and Seek”.
Giải giúp mik câu đại với ạ , giúp mik vẽ hình bài hình luoon đc ko ạ !! Giúp mik với mik cần gấp lắm !! Các bạn giải chi tiết giúp mik
Câu 3:
a: \(BD=\sqrt{BC^2-DC^2}=4\left(cm\right)\)
b: \(\widehat{A}=180^0-2\cdot70^0=40^0< \widehat{B}\)
nên BC<AC=AB
c: Xét ΔEBC vuông tại E và ΔDCB vuông tại D có
BC chung
\(\widehat{EBC}=\widehat{DCB}\)
Do đó:ΔEBC=ΔDCB
d: Xét ΔOBC có \(\widehat{OBC}=\widehat{OCB}\)
nên ΔOBC cân tại O
Câu 2
a) Thay y = -2 vào biểu thức đã cho ta được:
2.(-2) + 3 = -1
Vậy giá trị của biểu thức đã cho tại y = -2 là -1
b) Thay x = -5 vào biểu thức đã cho ta được:
2.[(-5)² - 5] = 2.(25 - 5) = 2.20 = 40
Vậy giá trị của biểu thức đã cho tại x = -5 là 40
Giúp mik câu 3 với ạ gấp lắm
Câu 3.
Công suất tỏa nhiệt:
\(P=U\cdot I=R\cdot I^2=70\cdot2^2=280W\)
Nhiệt lượng đun sôi 1,5l nước:
\(Q_{thu}=mc\Delta t=1,5\cdot4200\cdot\left(100-35\right)=409500J\)
Công mà bếp tiêu thụ:
\(A=UIt=70\cdot2\cdot2\cdot30\cdot60=504000J\)
Hiệu suất bếp:
\(H=\dfrac{Q_i}{A}\cdot100\%=\dfrac{409500}{504000}\cdot100\%=81,25\%\)
Giúp mik những câu chưa làm với ạ, mik cảm ơn nhiều lắm >
người ơi giúp mik với mik đg cần gấp lắm ạ!! Còn 20p nữa là mik học rồi nhưng mik vẫn còn 3 câu chx tính xong, mọi người giúp mik với ạ, cho mik câu trả lời chi tiết và rõ ràng các bước nhất với ạ!, mi cảm ơn! Xong thì mik sẽ tick ạ( cái ảnh thứ nhất là cách làm ạ.)
a: \(=\dfrac{x^3+2x+2x-2-x^2-x-1}{\left(x-1\right)\left(x^2+x+1\right)}\)
\(=\dfrac{x^3-x^2+3x-3}{\left(x-1\right)\left(x^2+x+1\right)}=\dfrac{x^2+3}{x^2+x+1}\)
b: \(=\dfrac{x^2-2x-3+x^2+2x-3+2x-2x^2}{\left(x-3\right)\left(x+3\right)}\)
\(=\dfrac{2x-6}{\left(x-3\right)\left(x+3\right)}=\dfrac{2}{x+3}\)
c: \(=\dfrac{6-7+x}{3\left(x-1\right)}=\dfrac{x-1}{3\left(x-1\right)}=\dfrac{1}{3}\)
d: \(=\dfrac{x^3+2x+2x-2-x^2-x-1}{\left(x-1\right)\left(x^2+x+1\right)}=\dfrac{x^3-x^2+3x-3}{\left(x-1\right)\left(x^2+x+1\right)}=\dfrac{x^2+3}{x^2+x+1}\)