6. Tính các tổng sau: a) S, =1+(-2)+3+(4)+...+(-2018)+ 2019 ; b) S, =(-2)+4+(-6)+8+.+(-2018)+ 2020; c) S, =1+(-3)+5+(-7)+..+2017+(-2019); d) S, =(-2015)+(-2014)+(-2013)+..+2019+2020

CMR:nếu 2n+1 và 3n+1 đều là số chính phương thì n chia hết cho 40

Giúp mình giải câu sáừ với các bạn ơi

9)Tìm các số tự nhiên a, b, c sao choA=a^2(b+c) + b^2(c+a) +c^2(a+b) là số nguyên tố

ở người 2n=46 , 1 tế bào sinh dục sơ khai nguyên phân liên tiếp 3 lần tại các tế bào con . Các đều bước vào giảm phân tại giao đực tử a, tính số tinh trùng tạo thành b, xác định số NST đơn có trong tất cả các tinh trùng c, xác định số nst mtcc cho nguyên phân và giảm phân tại tinh trùng

EX1. Choose the underlined letter that pronouned different from others. 1-A. sugar B. soda C. sometimes D. sandwich 2-A. catch B. touch C. chopstick D. stomach 3-A. decided B. visited C. stopped D.collected 4-A. great B. beach C. teacher D. meat 5. A. aquarium B. arrive C. again D. ate 6. A. looks B. books C.names D. students 7. A. looked B. stopped C. washed D. visited 8. A. other B. then C. both D. brother 9A. add B. balanced C. affect D. pan 10. A. spoon B. look C. book D. foot 11. A. without B. about C. loud D. cough 12. A. ruler B. very C. iron D. ripe 13. A. say B. cap C. plane D. name 14. A. touch B. watch C. machine D. armchair 15. A. famous B. nervous C. loud D. serious 16. A. scared B. added C. drilled D. explained .17 a. laughed b. looked c. collected d. missed 18. a. asked b. missed c. called d. cooked 19. a. changed b. measured c. brushed d.moved 20. a. decided b. loved c. wanted d. started II. Find a mistake in the four underlined part of each sentence and correct it. 1. This movie is not more interesting as the one we saw last week. 2. My brother never enjoys classical music and I don’t too. 3. The author of this novel is the same like that one. 4. The concert show was quite different than what I thought. 5. Hoang is very interested in rock and roll and his classmates are either. 6. His performance is amazed. Every critic likes it. 7. Because there was an accident, nobody was hurt. 8. What about go to the zoo on foot? – It is a good idea. 9. She performed goodly in this movie. She received a lot of good reviews from critics. 10. You should to obey the traffic rules to avoid causing accidents EX3. Rewrite the following sentences in such a way that they mean the same as the original sentences. 1. It’s a good idea to eat a lot of fruit and vegetables every day. We should . 2. We couldn’t keep on cleaning the streets because of the heavy rain. Because it . 3. The garden party won’t take place if the weather doesn’t improve. Unless . 4. Both students and teachers can borrow books from the library. The library lends . 5. Nobody plays this piece of music as beautifully as he does. He plays this . 6. I like pop music but my brother likes rock music. (different) My taste in music………………………………………….....my brother. 7. Neither Mary nor her sister studied arts at school. (either) Mary never studied arts at school and ………………………………….. 8. I think Vinh acted better than Quang in that play. (as) I think Quang didn’t …………………………………...Vinh in that play. 9. Both Anna and her brother are fond of watching water puppet. (too) Anna is fond of watching water puppet and …………………………….. 10. My hobby is drawing and John’s hobby is also drawing. (same) My hobby …………………………………………………John’s hobby. EX4. Give the correct form of the words given to complete the sentence. ( từ loại) 1. Trà Giang is one of the most famous …………………..of Vietnam. Many people love her. (ACT) 2. The …………………..she gave last night was marvelous. (PERFORM) 3. The Đàn Bầu is a Vietnamese traditional …………………..instrument. (MUSIC) 4. I don’t like pop music because it is not as …………………..as rock and roll. (EXCITE) 5. Mai wanted to share her …………………..with other people. (PLEASE) 6. Trần Văn Cẩn is my favorite …………………..He is famous for the painting “Little sister Thuy” (Em Thúy). (ART) 7. …………………..is the art of taking and processing photographs. (PHOTOGRAPH) 8. Water puppetry …………………..in the villages of the Red River Delta. (ORIGIN) 9. Peter has received a letter of …………………..to see a water puppet show this Sunday. (INVITE) 10. I think a good knowledge of arts and music is a …………………..for anyone. (NECESSARY

giải hộ mình với mình đang vội lắm rồi làm ơn

Giải bài toán bằng cách lập phương trình : Một người đi xe máy dự định đi từ A đến B với vận tốc 36km/h. Nhưng khi thực hiện người ấy giảm vận tốc 6km/h nên đã đến B chậm hơn dự định là 24 phút. Tính quãng đường AB

Bố cho anh 19 cái kẹo, anh lại Cho em 6 cái kẹo. Chị có số kẹo bằng số kẹo của cả hai anh em. Tính số kẹo của chị

Giải giúp mình 2 câu này ạ lý 10