Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Ta có: \(A=\frac{2x^2-16x+33}{x^2-8x+17}=\frac{\left(2x^2-16x+34\right)-1}{x^2-8x+17}\)
\(=2-\frac{1}{x^2-8x+17}\)
Ta thấy rằng A bé nhất khi x2 - 8x + 17 bé nhất
x2 - 8x + 17 = (x2 - 8x + 16) + 1 = (x - 4)2 + 1\(\ge1\)
=> x2 - 8x + 17 bé nhất = 1 khi x = 4
Vậy A bé nhất bằng 2 - 1 = 1 khi x = 4
Gọi điểm môn Toán bạn An cần làm là x(điểm)
(Điều kiện: x>0)
Trung bình điểm kiểm tra của An là: \(\dfrac{8\cdot2+7+9+x\cdot2}{2+1+2+1}=\dfrac{2x+32}{6}\)
Để đạt từ 8,0 trở lên thì \(\dfrac{2x+32}{6}>=8\)
=>2x+32>=48
=>2x>=16
=>x>=8
vậy: An cần ít nhất 8 điểm môn Toán để được xếp loại giỏi
TIẾNG ANH:
Đề kiểm tra 1 tiết môn Tiếng Anh lớp 8
A. PHONES: (1p)
1. A. children B. chicken C. chair D. character
2. A. curly B. shy C. fly D. sky
3. A. joke B. local C. blond D. sociable
4. A. fourteen B. volunteer C. seem D. free
B. LANGUAGE FOCUS: (3ps)
I. Choose A, B, C, D for each gap in the following sentence. (2ps)
1. "Would you_________ to go to the movies with me?" – "I'd love to."
A. B. want C. love D. mind
2. He is not ____________ get married.
A. enough old to B. enough old for C. old enough to D. old enough for
3. Her mother ____________this city two years ago.
A. left B. leaves C. is leaving D. will leave
4. Alexander Graham Bell was born __________ March 3, 1847.
A. in B. on C. at D. during
5. Don't come in. Please wait _________ for your turn.
A. inside B. downstairs C. outside D. upstairs
6. The children are old enough to look after __________.
A. themselves B. ourselves C. herself D. for themselves
7. We ought __________ the wardrobe in the corner opposite the bed.
A. put B. putting C. to put D. puts
8. The calendar is ________ the clock, _________ the picture and the lamp.
A. on/next to B. under/between C. behind/between D. above/on
II. Supply the correct form of the verbs in the blanket. (1p)
1. We usually (go) ___________ to the library three times a week, but last week we (go) __________ twice.
2. Nga and Hoa (see) __________________ a movie tonight.
3. Sue can (speak) _______________ Vietnamese very well.
C. READING: (2ps)
I. Read the text and k in the true/ false column: (1p)
Do you have any close friends? I have two close friends, Hanh and Mai. We are in the same class. We are also neighbors. Hanh is a beautiful girl with big black eyes and an oval rosy face. She is an intelligent student who is always at the top of the class. She s reading, and she often goes to the library whenever she has free time. Mai isn't as beautiful as Hanh, but she has a lovely smile and looks very healthy. Mai is very sporty. She is a volleyball star of our school. She is very sociable and has a good sense of humor. I love both of my friends and I always hope our friendship will never die.
Statements | True | False |
1. The writer has two close friends. | ||
2. They are in the same class. | ||
3. Mai s reading. | ||
4. Hanh s sports. |
II. Read the text and answer the questions: (1p)
1. What does Hanh look ?
→ ...........................................................................................
2. Is she intelligent?
→ ...........................................................................................
3. What does Mai look ?
→ ...........................................................................................
4. Is she shy?
→ ...........................................................................................
D. WRITING: (4 ps)
I. Complete each sentence so it means the same as the sentence above. (2ps)
1. Peter is too young to see the horror film.
→ Peter is not old ...................................................................................
2. Hoa is older than Nien.
→ Nien is ...............................................................................................
3. The cat is on the gas stove.
→ The gas stove is ..................................................................................
4. Her hair is long and black.
→ She has ...............................................................................................
II. Put the words or phrase in correct order to make sentences. (2ps)
1. enough/ Jane/ strong/ the box./ to/ is/ lift
→ .................................................................................................................
2. you/ going to/ are/ What/ do/ next weekend?
→ .................................................................................................................
3. is/ Mai./ beautiful/ more/ Hanh/ than
→ .................................................................................................................
4. awful/ an/ What/ house!
→ ................................................................................................................
THE END -
ANSWER KEY:
A. PHONES: (1p)
1. A. children B. chicken C. chair D. character
2. A. curly B. shy C. fly D. sky
3. A. joke B. local C. blond D. sociable
4. A. fourteen B. volunteer C. seem D. free
B. LANGUAGE FOCUS: (3ps)
I. Choose A, B, C, D for each gap in the following sentence. (2ps)
1. “Would you_________ to go to the movies with me?” – “I’d love to.”
B. want C. love D. mind
2. He is not ____________ get married.
enough old to B. enough old for C. old enough to D. old enough for
3. Her mother ____________this city two years ago.
left B. leaves C. is leaving D. will leave
4. Alexander Graham Bell was born __________ March 3, 1847.
in B. on C. at D. during
5. Don’t come in. Please wait _________ for your turn.
inside B. downstairs C. outside D. upstairs
6. The children are old enough to look after __________.
themselves B. ourselves C. herself D. for themselves
7. We ought __________ the wardrobe in the corner opposite the bed.
put B. putting C. to put D. puts
8. The calendar is ________ the clock, _________ the picture and the lamp.
on/next to B. under/between C. behind/between D. above/on
II. Supply the correct form of the verbs in the blanket. (1p)
1. We usually (go) ___ go ________ to the library three times a week, but last week we (go) __went________ twice.
2. Nga and Hoa (see) __will see / are going to see_____ a movie tonight.
3. Sue can (speak) ____ speak _____ Vietnamese very well.
C. READING: (2ps)
I. Read the text and k in the true/ false column: (1p)
Do you have any close friends? I have two close friends, Hanh and Mai. We are in the same class. We are also neighbors. Hanh is a beautiful girl with big black eyes and an oval rosy face. She is an intelligent student who is always at the top of the class. She s reading, and she often goes to the library whenever she has free time. Mai isn’t as beautiful as Hanh, but she has a lovely smile and looks very healthy. Mai is very sporty. She is a volleyball star of our school. She is very sociable and has a good sense of humor. I love both of my friends and I always hope our friendship will never die.
Statements | True | False |
1. The writer has two close friends. | √ | |
2. They are in the same class. | √ | |
3. Mai s reading. | √ | |
4. Hanh s sports. | √ |
II. Read the text and answer the questions: (1p)
1. What does Hanh look ?
→ She is a beautiful girl with big black eyes and an oval rosy face.
2. Is she intelligent?
→ Yes, she is.
3. What does Mai look ?
→ She has a lovely smile and looks very healthy.
4. Is she shy?
→No, she isn’t.
D. WRITING: (4 ps)
I. Complete each sentence so it means the same as the sentence above. (2ps)
1. Peter is too young to see the horror film.
→ Peter is not old enough to see the horror film.
2. Hoa is older than Nien.
→ Nien is younger than Hoa.
3. The cat is on the gas stove.
→ The gas stove is under the cat.
4. Her hair is long and black.
→ She has long black hair.
II Put the words or phrase in correct order to make sentences. (2ps)
1. enough / Jane / strong / the box./ to / is / lift
→ Jane is strong enough to lift the box.
2. you / going to / are / What / do / next weekend?
→ What are you going to do next weekend?
3. is / Mai. / beautiful / more/ Hanh /...
gọi điểm kiểm tra học kì của Tiến để đạt được hsg là x ( x>0) \(\Rightarrow\)theo đầu bài ta có tổng hệ số là 13 nên ta có phương trình sau :
\(\frac{9+9+9+6+8.2+8.2+9.2+3x}{13}\)= \(8\)
\(\Rightarrow\)75 + 3x = 104
\(\Rightarrow\)3x = 29
\(\Rightarrow\)x sấp sỉ 10 điểm thì thỏa mãn đk ủa ẩn và giúp điểm phảy trung bình của Đạt đạt loại giỏi
mỗi trường đề khác nhau mà, nếu muốn bạn lên mạng mà tìm ý, nhìu lắm!
I) TRẮC NGHIỆM: ( 2đ) Hãy khoanh tròn chữ cái đứng trước kết quả đúng
1/ Trong các hình sau, hình không có tâm đối xứng là:
A . Hình vuông B . Hình thang cân C . Hình bình hành D . Hình thoi
2/ Trong các hình sau, hình không có trục đối xứng là:
A . Hình vuông B . Hình thang cân C . Hình bình hành D . Hình thoi
3/ Một hình thang có 2 đáy dài 6cm và 4cm. Độ dài đường trung bình của hình thang đó là:
A . 10cm B . 5cm C . √10 cm D . √5cm
4/ Tứ giác có hai cạnh đối song song và hai đường chéo bằng nhau là:
A . Hình vuông B . Hình thang cân C . Hình bình hành D . Hình chữ nhật
5/ Một hình thang có một cặp góc đối là: 1250 và 650. Cặp góc đối còn lại của hình thang đó là:
A . 1050 ; 450 B . 1050 ; 650
C . 1150 ; 550 D . 1150 ; 650
6/ Cho tứ giác ABCD, có ∠A = 800; ∠B =1200, ∠D = 500. Số đo góc C là?
A. 1000 ,
B.1500,
C.1100,
D. 1150
7/ Góc kề 1 cạnh bên hình thang có số đo 750, góc kề còn lại của cạnh bên đó là:
A. 850 B. 950
C.1050
D.1150
8/ Độ dài hai đường chéo hình thoi là 16 cm và 12 cm. Độ dài cạnh của hình thoi đó là:
A 7cm,
B.8cm,
C.9cm,
D.10 cm
II/TỰ LUẬN (8đ)
Bài 1: ( 2,5 đ) Cho tam giác ABC cân tại A, M là trung điểm của BC, Từ M kẻ các đường ME song song với AC ( E ∈ AB ); MF song song với AB ( F ∈ AC ). Chứng minh Tứ giác BCEF là hình thang cân.
Bài 2. ( 5,5đ)Cho tam giác ABC góc A bằng 90o. Gọi E, G, F là trung điểm của AB, BC, A
C.Từ E kẻ đường song song với BF, đường thẳng này cắt GF tại I.
a) Tứ giác AEGF là hình gì ?
b) Chứng minh tứ giac BEIF là hình bình hành
c) Chứng minh tứ giác AGCI là hình thoi
d) Tìm điều kiện để tứ giác AGCI là hình vuông.
Bài 1
1-3
2-1
3-2
bài 2
D