[HÓA 10- SỰ KIỆN GIẢI ĐỀ CỦNG CỐ KIẾN THỨC HKI - CÂU SỐ 1]
Mọi người tham gia giải đề hỏi đáp nha!
Đề trích câu 5 từ đề thi HKI Hóa 10 trường THPT Trần Khai Nguyên - TPHCM được bạn Anh Kỳ gửi về!
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HP
Hồng Phúc
17 tháng 1 2021
Đúng(7)
Những câu hỏi liên quan
MN
17 tháng 1 2021
Câu 1:
PTBD: biểu cảm, nghị luận (?)
Câu 2:
''đầy đủ, trong trẻo, đẹp đẽ sáng sủa và sang giàu''
Câu 3:
Tác giả cảm thấy tự hào, biết ơn và may mắn khi được nói tiếng Việt. Tác giả đã ''chịu ơn rất nhiều đối với quê hương ông bà'' cho thấy niềm tự hào to lớn của tác giả đối với ''thứ tiếng nói đậm đà'' đó
NN
17 tháng 1 2021
21 communication
22 miraculous
23 opposed
24 gradually
25 different
26 enjoyably
27 accurate
28 transmission
29 comes
30 was going
31 helping
32 to dip
33 am doing
34 haven't met
35 to choose
HN
17 tháng 1 2021
21 communication
22 miraculous
23 opposed
24 gradually
25 different
26 enjoyably
27 accurate
28 transmission
29 comes
30 was going
31 helping
32 to dip
33 am doing
34 haven't met
35 to choose
17 tháng 1 2021
Câu 4b:
Ta có \(a-\sqrt{a}=\sqrt{b}-b\Leftrightarrow a+b=\sqrt{a}+\sqrt{b}\). (1)
Áp dụng bất đẳng thức Cauchy - Schwarz ta có:
\(a^2+b^2\ge\dfrac{\left(a+b\right)^2}{2};\sqrt{a}+\sqrt{b}\le\sqrt{2\left(a+b\right)}\).
Kết hợp với (1) ta có:
\(a+b\le\sqrt{2\left(a+b\right)}\Leftrightarrow0\le a+b\le2\).
Ta có: \(P\ge\dfrac{\left(a+b\right)^2}{2}+\dfrac{2020}{\left(\sqrt{a}+\sqrt{b}\right)^2}\) (Do \(a^2+b^2\ge\dfrac{\left(a+b\right)^2}{2}\))
\(=\dfrac{\left(a+b\right)^2}{2}+\dfrac{2020}{\left(a+b\right)^2}\) (Theo (1))
\(\Rightarrow P\ge\dfrac{\left(a+b\right)^2}{2}+\dfrac{2020}{\left(a+b\right)^2}\).
Áp dụng bất đẳng thức AM - GM cho hai số thực dương và kết hợp với \(a+b\le2\) ta có:
\(\dfrac{\left(a+b\right)^2}{2}+\dfrac{2020}{\left(a+b\right)^2}=\left[\dfrac{\left(a+b\right)^2}{2}+\dfrac{8}{\left(a+b\right)^2}\right]+\dfrac{2012}{\left(a+b\right)^2}\ge2\sqrt{\dfrac{\left(a+b\right)^2}{2}.\dfrac{8}{\left(a+b\right)^2}}+\dfrac{2012}{2^2}=4+503=507\)
\(\Rightarrow P\ge507\).
Đẳng thức xảy ra khi a = b = 1.
Vậy Min P = 507 khi a = b = 1.
17 tháng 1 2021
Giải nốt câu 4a:
ĐKXĐ: \(x\geq\frac{-1}{2}\).
Phương trình đã cho tương đương:
\(x^2+2x+1=2x+1+2\sqrt{2x+1}+1\)
\(\Leftrightarrow\left(x+1\right)^2=\left(\sqrt{2x+1}+1\right)^2\)
\(\Leftrightarrow\left(x+1\right)^2-\left(\sqrt{2x+1}+1\right)^2=0\)
\(\Leftrightarrow\left(x+1-\sqrt{2x+1}-1\right)\left(x+1+\sqrt{2x+1}+1\right)=0\)
\(\Leftrightarrow\left(x-\sqrt{2x+1}\right)\left(x+\sqrt{2x+1}+2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-\sqrt{2x+1}=0\left(1\right)\\x+\sqrt{2x+1}+2=0\left(2\right)\end{matrix}\right.\).
Ta thấy \(x+\sqrt{2x+1}+2>0\forall x\ge-\dfrac{1}{2}\).
Do đó phương trình (2) vô nghiệm.
Xét phương trình (1) \(\Leftrightarrow x=\sqrt{2x+1}\)
\(\Leftrightarrow\left\{{}\begin{matrix}x\ge0\\x^2=2x+1\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x\ge0\\\left(x-1\right)^2=2\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x\ge0\\\left[{}\begin{matrix}x-1=\sqrt{2}\\x-1=-\sqrt{2}\end{matrix}\right.\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x\ge0\\\left[{}\begin{matrix}x=\sqrt{2}+1>0>-\dfrac{1}{2}\left(TM\right)\\x=-\sqrt{2}+1< 0\left(\text{loại}\right)\end{matrix}\right.\end{matrix}\right.\).
Vậy nghiệm của phương trình là \(x=\sqrt{2}+1\).
HT
17 tháng 1 2021
Nguồn 8 pin mà vẽ 2 pin, chậc chậc :v
a/ \(\xi=8.E=24\left(V\right)=U_V\)
\(r_b=8r=8.0,25=2\left(\Omega\right)\)
\(R_2=\dfrac{U^2_{dm}}{P_{dm}}=\dfrac{36}{3}=12\left(\Omega\right);I_{dm}=\dfrac{P_{dm}}{U_{dm}}=\dfrac{3}{6}=\dfrac{1}{2}\left(A\right)\)
\(PTMD:R_4nt\left[\left(R_1ntR_2\right)//R_3\right]\) \(\Rightarrow R_{td}=R_4+\dfrac{\left(R_1+R_2\right).R_3}{R_1+R_2+R_3}=...\left(\Omega\right)\)
\(\Rightarrow I=I_A=\dfrac{\xi}{R_{td}+R}=\dfrac{24}{2+R_{td}}=...\left(A\right)\)
b/ \(I_4=I\Rightarrow U_4=R_4.I=...\left(V\right)\)
\(\Rightarrow U_{12}=U_3=\xi-I.r-U_4=...\left(V\right)\)
\(\Rightarrow I_{12}=I_2=\dfrac{U_{12}}{R_1+R_2}=...\left(A\right)\)
\(\left[{}\begin{matrix}I_2< I_{dm}\Rightarrow den-sang-yeu-hon-binh-thuong\\I_2>I_{dm}\Rightarrow den-sang-manh-hon-binh-thuong\\I_2=I_{dm}\Rightarrow den-sang-binh-thuong\end{matrix}\right.\)
P/s: Thầy cô thông cảm em vừa ngủ dậy nên lười dậy lấy máy tính tính toán lắm ạ :(
17 tháng 1 2021
Đề này của Chuyên LHP - TPHCM không phải Chuyên LHP - Nam Định nha mọi người!
Đề này được bạn Anh Kỳ gửi! (https://hoc24.vn/vip/202859493659)
K
15 tháng 4 2021
1: Only with careful environmental planning can we protect the world in which we live.
D. We can protect the world we live in only with careful environmental planning.
2: You should take regular exercises instead of sitting in front of the television all day.
A. Taking regular exercises is better than sitting in front of the television all day.
3: It was not until after I got home that I realized I had not set the burglar alarm in the office.
C. I didn’t turn the burglar alarm on before I left the office, but I only became aware of this after I'd arrived home.
4: He did not remember the meeting. He went out for a coffee with his friends then.
D. Not remembering the meeting, he went out for a coffee with his friends.
5: They left their home early. They didn’t want to miss the first train.
C. They left their home early so as not to miss the first train.
6: I’m sure Luisa was very disappointed when she failed the exam
B. Luisa must have been very disappointed when she failed the exam.
7. “You had better see a doctor if the sore throat does not clear up.” she said to me.
D. She suggested that I see a doctor if the sore throat did not clear up.
8: Without her teacher’s advice, she would never have written such a good essay
C. She wrote a good essay as her teacher gave her some advice.
9. She tried very hard to pass the driving test. She could hardly pass it.
C. No matter how hard she tried, she could hardly pass the driving test.
10. Mary loved her stuffed animal when she was young. She couldn’t sleep without it.
A. When Mary was young, she loved her stuffed animal so much that she couldn't sleep without it.
DT
Đỗ Thanh Hải
CTVVIP
15 tháng 4 2021
1: Only with careful environmental planning can we protect the world in which we live.
A. Careful environmental planning protects the world we live in.
B. Planning the environment carefully, we can protect the world in which we live.
C. Protecting the world we live in, we plan the environment carefully.
D. We can protect the world we live in only with careful environmental planning.
2: You should take regular exercises instead of sitting in front of the television all day.
A. Taking regular exercises is better than sitting in front of the television all day.
B. Sitting in front of the television all day helps you take regular exercises.
C. Sitting in front of the television all day and taking exercises are advisable.
D. Don’t take regular exercises, just sit in front of the television all day.
3: It was not until after I got home that I realized I had not set the burglar alarm in the office.
A. On the way home, I suddenly realized that I had forgotten to turn on the burglar alarm in the office.
B. Fortunately, I realized that I hadn't set the burglar alarm just before I left for home; otherwise, I would have had to travel all the way back to the office.
C. I didn’t turn the burglar alarm on before I left the office, but I only became aware of this after I'd arrived home.
D. I wish I had realized before I arrived home that I hadn't turned on the burglar alarm in the office, then it would have been easier to go and set it.
4: He did not remember the meeting. He went out for a coffee with his friends then.
A. Not remember the meeting, he went out for a coffee with his friends.
B. Not to remember the meeting, he went out for a coffee with his friends.
C. Not remembered the meeting, he went out for a coffee with his friends.
D. Not remembering the meeting, he went out for a coffee with his friends.
5: They left their home early. They didn’t want to miss the first train.
A. They left their home early so as to not miss the first train.
B. They left their home early for fear that they wouldn’t miss the first train.
C. They left their home early so as not to miss the first train.
D. They left their home early in order that not to miss the first train.
6: I’m sure Luisa was very disappointed when she failed the exam
A. Luisa must be very disappointed when she failed the exam.
B. Luisa must have been very disappointed when she failed the exam.
C. Luisa may be very disappointed when she failed the exam.
D. Luisa could have been very disappointed when she failed the exam.
