Giair giúp mk cái đề dưới phần bình luận ik
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TS
3
KV
1 tháng 11 2023
a) ∠CEz + ∠zEy' = 180⁰ (kề bù)
⇒ ∠CEz = 180⁰ - ∠zEy'
= 180⁰ - 120⁰
= 60⁰
⇒ ∠CEz = ∠xDz = 60⁰
Mà ∠CEz và ∠xDz là hai góc đồng vị
⇒ xx' // yy'
b) Do HC ⊥ xx' (gt)
xx' // yy' (cmt)
⇒ HC ⊥ yy'
c) Do HC ⊥ yy' (cmt)
⇒ ∠HCy = 90⁰
⇒ ∠BCy = ∠HCy - ∠BCH
= 90⁰ - 40⁰
= 50⁰
c) Vẽ tia Bt // xx'//yy'
⇒ ∠CBt = ∠BCy = 50⁰ (so le trong)
⇒ ∠ABt = ∠ABC - ∠CBt
= 90⁰ - 50⁰
= 40⁰
Do Bt // xx'
⇒ ∠xAB = ∠ABt = 40⁰ (so le trong)
Ta có:
∠BAx' + ∠xAB = 180⁰ (kề bù)
⇒ ∠BAx' = 180⁰ - ∠xAB
= 180⁰ - 40⁰
= 140⁰
e) Do AB cắt tia Bt tại B
Mà Bt // yy'
⇒ AB cắt yy'
VT
2
NN
29 tháng 12 2022
a, Diện tích khu vườn hình thang là:
\(\left(60+80\right)\times50:2=3500m^2\)
b, Diện tích bồn đất trồng hoa là:
\(18\times25=450m^2\)
c,Ta có: \(450=200.2+50\)
Vậy cần ít nhất 3 túi giống rau để gieo hết phần đất trồng rau.
5 tháng 1 2021
\(A^3_n+5A^2_n=2\left(n+15\right)\)
ĐK: n ≥ 3 (n∈N)
<=> \(\dfrac{n!}{\left(n-3\right)!}+\dfrac{5.n!}{\left(n-2\right)!}=2\left(n+15\right)\)
<=> \(\dfrac{n\left(n-1\right)\left(n-2\right)\left(n-3\right)!}{\left(n-3\right)!}+\dfrac{5n\left(n-1\right)\left(n-2\right)!}{\left(n-2\right)!}=2\left(n+15\right)\)
<=> \(n\left(n-1\right)\left(n-2\right)+5\left(n-1\right)n-2n-30=0\)
<=> \(n^3+2n^2-5n-30=0\) <=> n=3
8 tháng 12 2023
Để hệ phương trình có nghiệm duy nhất thì \(\dfrac{m}{3}< >-\dfrac{1}{m}\)
=>\(m^2\ne-3\)(luôn đúng)
Ta có: \(\left\{{}\begin{matrix}mx-y=2\\3x+my=3m\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}y=mx-2\\3x+m\left(mx-2\right)=3m\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}y=mx-2\\3x+m^2x-2m=3m\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}y=mx-2\\x\left(m^2+3\right)=5m\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{5m}{m^2+3}\\y=m\cdot\dfrac{5m}{m^2+3}-2\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}x=\dfrac{5m}{m^2+3}\\y=\dfrac{5m^2-2m^2-6}{m^2+3}=\dfrac{3m^2-6}{m^2+3}\end{matrix}\right.\)
\(\left(x+y\right)\cdot\left(m^2+3\right)+8=0\)
=>\(\dfrac{5m+3m^2-6}{m^2+3}\cdot\left(m^2+3\right)+8=0\)
=>\(3m^2+5m-6+8=0\)
=>\(3m^2+5m+2=0\)
=>(m+1)(3m+2)=0
=>\(\left[{}\begin{matrix}m=-1\\m=-\dfrac{2}{3}\end{matrix}\right.\)
21 tháng 7 2023
d: \(=\dfrac{-9\sqrt{3}-6\sqrt{2}}{19}-\dfrac{\sqrt{3}}{5}\)
\(=\dfrac{-64\sqrt{3}-30\sqrt{2}}{95}\)
b: \(=\dfrac{37\left(7-2\sqrt{3}\right)}{49-12}=7-2\sqrt{3}\)
TS
3
PH
7
28 tháng 5 2021
I. Phonics:
Odd one out:
| 1. A. story | B. worry | C. fly | D. study |
| 2. A. ride | B. | C. nice | D. fish |
| 3. A. fever | B. very | C. bed | D. well |
| 4. A. school | B. chocolate | C. child | D. children |
| 5. A. many | B. animal | C. engineer | D. friend |
Odd one out:
| 6. A. singer | B. worker | C. farmer | D. engineer |
| 7. A. cartoon | B. programme | C. music | D. classroom |
| 8. A. garden | B. question | C. delicious | D. water |
| 9. A. intelligent | B. greedy | C. princess | D. favourite |
| 10. A. character | B. apple | C. because | D. stupid |
II. Vocabulary:
Odd one out:
| 11. A. engineer | B. teacher | C. farm | D. doctor |
| 12. A. stomachache | B. headache | C. fever | D. school |
| 13. A. bike | B. motorbike | C. plane | D. comic |
| 14. A. write | B. read | C. song | D. sleep |
| 15. A. apple | B. fox | C. elephant | D. lion |
Choose the correct answer:
16. What would you to be in the future? – I’d to be _____ writer.
A. a
B. an
C. Ø
D. the
17. I think Tam is _______.
A. greedy
B. kind
C. ugly
D. stupid
18. My favourite book is _______.
A. comics
B. songs
C. TV
D. children
19. The main character in Snow White is _______.
A. the princess
B. Snow White
C. Doraemon
D. Tom
20. Trung would to be a _______ in the future.
A. pilot
B. engineer
C. artist
D. architect
21. What are you doing? – I am _______ my favourite books.
A. read
B. reading
C. listen
D. listening
22. Nam has a high temperature. He has a/an _______.
A. earache
B. stomachache
C. fever
D. toothache
23. Why do you would to be a teacher? - _______ I’d to teach children.
A. When
B. Because
C. What
D. Where
24. Why would you to be a nurse? - _______.
A. Because I would to look after the patients.
B. Because I would to teach the children.
C. Because I would to write stories for children.
D. Because I would to fly a plane.
25. Linda has a pain in her throat. She has a/an _______.
A. toothache
B. sore throat
C. earache
D. backache
26. Don’t ride your _____ so fast!
A. car
B. matches
C. bike
D. stairs
27. You shouldn’t play with the knife because it’s _______.
A. small
B. sharp
C. tall
D. deep
28. What is she doing? – She _______ with matches.
A. are playing
B. was playing
C. is playing
D. am playing
29. What’s the ______ with you, Tony? – I’ve got a fever.
A. problem
B. matter
C. happiness
D. luck
30. What do you do in your free time? – I surf _______.
A. the Internet
B. comics
C. homework
D. flowers
31. John is riding his bike _______ the park.
A. on
B. at
C. above
D. in
32. I love karate. I _______ karate every day.
A. work
B. make
C. do
D. clean
33. Hoa often _______ to the music club every Sunday.
A. goes
B. does
C. listens
D. climbs
34. They _______ and singing songs.
A. dancing
B. climbing
C. going
D. doing
35. A: Thanks for your lovely gift.
B: ________.
A. You’re welcome
B. Go ahead!
C. I’m sorry!
D. Don’t worry about it!
36. Quan has a pain in his stomach. He has a/an _______.
A. toothache
B. stomach ache
C. sore throat
D. headache
III. READING
Task 1. Look and write the correct words.
Toothache/ bus stop/ pilot/ rice/ The story of Tam and Cam/
37. It’s a fairy tale about two sisters. ______________
38. He has a pain in her tooth. ________________
39. A person who flies or is qualified to fly an aircraft or spacecraft. ____________
40. A Southeast Asian grass widely grown in warm wet areas especially for its seeds which are used for food. _________________
41. A place where a bus regularly stops, usually marked by a sign. _________________
Task 3: Read and answer the questions.
Hi, I’m Mai. My hobby is reading folk tales. Folk tales are usually short and interesting. They often give me one surprise after another. The character are sometimes honest, sometimes greedy, sometimes wise, and sometimes stupid. I The Fox and the Crow very much. The Fox was clever and the Crow was not. The Crow lost its delicious meat and the Fox got it. I love folk tales very much because each of them gives me a lesson in life.
49. What kinds of stories does Mai reading?
____________________________________________________.
50. What does she think of folk tales?
____________________________________________________.
51. What does she think of the characters in folk tales?
____________________________________________________.
52. What does she think of the characters in The Fox and the Crow?
_________________________________________________
CT
28 tháng 5 2021
35 đề thi học kì 2 môn tiếng Anh lớp 5 năm 2021 có đáp án - 35 Đề thi tiếng Anh lớp 5 học kì 2 năm 2020 - 2021 - VnDoc.com
Bài 4 :
a) Xét \(\Delta AMB\) và \(\Delta AMC\) có :
AB = AC (gt)
\(AM:chung\)
\(BM=MC\left(gt\right)\)
=> \(\Delta AMB\) = \(\Delta AMC\) (c.c.c)
Xét \(\Delta ABC\) có :
AB = AC (gt)
=> \(\Delta ABC\) cân tại A
Mà có : M là trung điểm của BC
Thì : AM là đường trung tuyến trong tam giác cân
=> AM đồng thời là đường trung trực trong tam giác (tính chất tam giác cân)
\(\Rightarrow AM\perp BC\) (đpcm)
b) Xét \(\Delta ADF\) và \(\Delta CDE\) có :
\(AD=DC\left(gt\right)\)
\(\widehat{ADF}=\widehat{CDE}\) (đối đỉnh)
\(FD=DE\left(gt\right)\)
=> \(\Delta ADF\) = \(\Delta CDE\) (c.g.c)
=> \(\widehat{FAD}=\widehat{ECD}\) (2 góc tương ứng)
Mà 2 góc này ở vị trí so le trong
=> \(\text{AF // EC}\) (đpcm)