19.42:5.8 bằng bao nhiều vầy(giúp mình với)
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Tuổi con chiếm 1 phần thì tuổi mẹ chiếm 5 phần
Khi tuổi mẹ gấp 8 lần tuổi con thì:
Tuổi con là :
28 : (5 - 1) = 7(tuổi)
Tuổi mẹ là:
7 x 5 = 35(tuổi)
bạn thêm lênh xóa màn hình vào chương trình đi, nhìn nó sẽ gọn hơn đấy
lệnh clrscr; ngay dưới begin luôn
In this section you must choose the word or phrase which best completes each sentence. Circle the letter A, B, C or D against the number of each item 1-20 for the word or phrase you choose. (20 points)
1. My sister is very fond .................... chocolate candy.
A. of B. about C. with D. at
2. I have studied English ....................eight months.
A. for B. since C. by D. in
3. Listen ....................our teacher !
A. with B. to C. for D. in
4. There isn’t ....................food in the house.
A. none B. no C. some D. any
5. He arrives …………………..at six o’clock.
A. at home B. home C. in home D. to home
6. Herbert has had his car………………….. 1999.
A. ago B. since C. to D. for
7. How long will it ....................to get there ?
A. cost B. lose C. make D. take
8. I ....................it to you if you don’t have one.
A. give B. gave C. will give D. would give
9. ....................your homework yet ?
A. Did you finished B. Are you finishing C. Do you finish D. Have you finished
10. It’s the best book I …………………..read.
A. have ever B. had ever C. will ever D. can ever
11. He looked very..................when I told him the news.
A. happily B. happy C. happiness D. was happy
12. She is ..................in history.
A. interests B. interested C. interesting D. being interest
13. Is the Eiffel Tower taller....................Big Ben ?
A. then B. than C. as D. of
14. At school, David was..................anyone else in his class.
A. as clever as B. as clever than C. cleverer as D. cleverest
15. She speaks French ....................than you.
A. more faster B. more fluently C. well D. the most fluently
16. It began to rain while we…………………..soundly.
A. slept B. were sleeping C. have slept D. are sleeping
17. She doesn’t coffee, does she ?
A. Yes, she doesn’t B. No, she does C. Yes, she did D. No, she doesn’t
18. I won't go to bed …………………..I finish my homework.
A. until B. when C. while D. since
19. Is this book ………………….. ? Yes, it's mine.
A. you're B. yours C. you D. your
20. …………………..do you come to school ? By bus
A. How B. What C. By D. When
Đặt A = \(\frac{1}{2.5}+\frac{1}{5.8}+...+\frac{1}{23.26}+\frac{1}{26.29}\)
3A = \(\frac{3}{2.5}+\frac{3}{5.8}+...+\frac{3}{23.26}+\frac{3}{26.29}\)
= \(\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+...+\frac{1}{23}-\frac{1}{26}+\frac{1}{26}-\frac{1}{29}\)
= \(\frac{1}{2}-\frac{1}{29}\)\(=\frac{27}{58}\)
A = \(\frac{27}{58}:3=\frac{9}{58}\)
\(\frac{1}{2.5}+\frac{1}{5.8}+...+\frac{1}{23.26}+\frac{1}{26.29}=\frac{1}{3}.\left(\frac{3}{2.5}+\frac{3}{5.8}+...+\frac{3}{23.26}+\frac{3}{26.29}\right)\)
\(=\frac{1}{3}.\left(\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+...+\frac{1}{23}-\frac{1}{26}+\frac{1}{26}-\frac{1}{29}\right)=\frac{1}{3}\left(\frac{1}{2}-\frac{1}{29}\right)\)
\(=\frac{1}{3}.\frac{27}{58}=\frac{9}{58}\)
\(\dfrac{4}{5}.\dfrac{6}{2}-\dfrac{4}{5}.\dfrac{8}{9}-\dfrac{1}{2}=\dfrac{12}{5}-\dfrac{32}{45}-\dfrac{1}{2}=\dfrac{76}{45}-\dfrac{1}{2}=\dfrac{107}{90}\)
\(=\dfrac{4}{5}.\dfrac{6}{2}-\dfrac{4}{5}.\dfrac{8}{9}-\dfrac{1}{2}.1\)
\(=\dfrac{4}{5}.\left(\dfrac{6}{2}-\dfrac{1}{2}\right).1\)
\(=\dfrac{4}{5}.\dfrac{5}{2}.1\)
\(=2.1\)
\(=2\)
\(A=\frac{5}{2.5}+\frac{5}{5.8}+\frac{5}{8.11}+...+\frac{5}{98.101}\)
\(=\frac{5}{2}-\frac{5}{5}+\frac{5}{5}-\frac{5}{8}+....+\frac{5}{98}-\frac{5}{101}\)
\(=\frac{5}{2}-\frac{5}{101}=\frac{495}{202}\)
\(\frac{5}{2\times5}+\frac{5}{5\times8}+\frac{5}{8\times11}+...+\frac{5}{98\times101}\)
\(=\frac{5}{3}\times\left(\frac{3}{2\times5}+\frac{3}{5\times8}+\frac{3}{8\times11}+...+\frac{3}{98\times101}\right)\)
\(=\frac{5}{3}\times\left(\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+...+\frac{1}{98}-\frac{1}{101}\right)\)
\(=\frac{5}{3}\times\left(\frac{1}{2}-\frac{1}{101}\right)\)
\(=\frac{5}{3}\times\frac{99}{202}=\frac{165}{202}\)
3x/2.5 + 3x/5.8 + 3x/8.11 + 3x/11.14 = 1/21
=> x . ( 3/2.5 + 3/5.8 + 3/8.11 + 3/11.14 ) = 1/21
=> x . ( 1/2.5 + 1/5.8 + 1/8.11 + 1/11.14 ) = 1/21
x . ( 1/2 - 1/5 + 1/5 - 1/8 + 1/8 - 1/11 + 1/11 - 1/14 ) = 1/21
x . ( 1/2 - 1/14 ) = 1/21
x . 3/7 = 1/21
x = 1/21 : 3/7
=> x = 1/9
\(\frac{3x}{2\cdot5}+\frac{3x}{5\cdot8}+\frac{3x}{8\cdot11}+\frac{3x}{11\cdot14}=\frac{1}{21}\)
<=> \(x\left(\frac{3}{2\cdot5}+\frac{3}{5\cdot8}+\frac{3}{8\cdot11}+\frac{3}{11\cdot14}\right)=\frac{1}{21}\)
<=> \(x\left(\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}\right)=\frac{1}{21}\)
<=> \(x\left(\frac{1}{2}-\frac{1}{14}\right)=\frac{1}{21}\)
<=> \(x\cdot\frac{3}{7}=\frac{1}{21}\)
<=> \(x=\frac{1}{9}\)
các bạn ghi luôn phép tính cho mik nha mik cần gấp
= 3,348275862 lận cho mình xin like