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: ( 9/4 + 16/5 + 25/6 ) - ( 5/4 - 14/5 + 47/8 ) =0. 78125
\(\left(\frac{9}{4}+\frac{16}{5}+\frac{25}{6}\right)-\left(\frac{5}{4}-\frac{14}{5}+\frac{47}{8}\right)\)
\(=\frac{9}{4}+\frac{16}{5}+\frac{25}{6}-\frac{5}{4}+\frac{14}{5}-\frac{47}{8}\)
\(=\left(\frac{9}{4}-\frac{5}{4}\right)+\left(\frac{16}{5}+\frac{14}{5}\right)+\left(\frac{25}{6}-\frac{47}{8}\right)\)
\(=1+6-\frac{41}{24}\)
\(=7-\frac{41}{24}=\frac{127}{24}\)
câu 5:
x=3,6
y=6,4
câu 6: chụp lại đề
câu 7:
a)ĐKXĐ: \(x\ge0\)
\(3\sqrt{x}=\sqrt{12}\\ \Rightarrow9x=12\\ \Rightarrow x=\dfrac{4}{3}\)
b) ĐKXĐ: \(x\ge6\)
\(\sqrt{x-6}=3\\ \Rightarrow x-6=9\\ \Rightarrow x=15\)
1. $(-5)^20$ > 0 do đây là lũy thừa có số mũ chẵn, cơ số âm; $(-8)^7$ < 0 do đây là lũy thừa có số mũ lẻ, cơ số ấm. Do đó $$(-5)^20$>(-8)^7$.
2. $2^20 +\dfrac{1}{2^21} + 1 - (2^19 +\dfrac{1}{2^20} + 1) = (2^20 - 2^19) + (\dfrac{1}{2^21} - \dfrac{1}{2^20}) + (1 - 1) = 2^19.(2-1) + (\dfrac{1}{2^21} - \dfrac{1}{2^20} = 2^19 - \dfrac{1}{2^20} + \dfrac{1}{2^21} > 0$.
1. Tầng = floor
2. Đường phố = Street
3. Quê hương = hometown
4. Vùng quê = countryside
5. Đất nước = country
6. Yên bình = Peaceful
7. Đông đúc = Crowded
8. Bận rộn = Busy
Mấy anh chị giúp em với ạ
3. I began living there in 2010..
→ I have..been living there since 2010...
4. They started to play football when they were 8 years old.
→They have.played football since they were 8 years old...
5. She began getting married 20 years ago.
→She has..been getting married for 20 years.....
6. He began to be a teacher 23 years ago.
=> He has been to be a teacher for 23 years
7. I haven't seen him since Christmas. →
The last time..I saw him was on Christmas day....
8. I haven't seen him since I left school.
→ The last time..I saw him when I left school.....
9. I haven't seen him for 8 years.
→The last time..I saw him ...was 8 days ago...
10. They haven't worked for this company since 1992.
→ The last time...they worked for this company was on 1992.....
11. They haven't worked for this company since they moved their houses →The last time...they worked for this company when they moved theire houses.....
12. They haven't worked for this company for 10 years.
→The last time...they worked for this company was 10 years ago .....
13. We have not studied in this school for nearly 3 years.
→The last time...we studied in this school was nearly 3 years ago....
14. We have not studied in this school since we were in grade 10.
→The last time...we studied in this school when we were in grade 10....
15. We have not studied in this school since last year.
→The last time...we studied in this school was on last year....
16. I got married her in 2000.
→I have..married her since 2000.
17.I got married her when I was 30 years old.
=>I have..married her since I was 30 years old..
18. I got married her 12 years ago.
=> I have.married her for 12 years..
19. I graduated from high school when I was 18 years old.
=>I have.graduated from high school since I was 18 years old...
20. We graduated from high school in 1999.
→We have.graduated from high school since 1999....
21. We graduated from high school 25 years ago.
=>We have..graduated from high school for 25 years..
22. I haven't seen Bob since I was in Ho Chi Minh City.
→ I last saw Bob when I was in Ho Chi Minh City
23. They've been using robots in this factory for ten years.
→ They started to use robots in this factory 10 years ago
24. Doctors and scientists been to fight against CORONA VIRUS two years ago.
→Doctors and scientists have.. been fighting against Corona virus for two years
25. We started learning in this school when we were 15 years old.
→ We have been learning in this school since we were 15 years old
26. Mary began to work in this company 5 years ago.
→Mary has worked in this company for 5 years
27. He last time she visited her home town when she was 25.
→ She hasn't visited her home town since she was 25
28. He last had his eyes tested 6 months ago.
→ He hasn't had his eyes tested for 6 months
âm 5 nhé em
=5 em nhe