Giúp mình với chiều mình đi học rồi
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NN
3
26 tháng 7 2023
$C=1+4+...+4^{6}$
$4C=4+4^{2}+...+4^{7}$
$4C-C=4+4^{2}+...+4^{7}-1-4-...-4^{6}$
$3C=4^{7}-1$
$C=\dfrac{4^{7}-1}{3}$
26 tháng 7 2023
Để tính tổng S = 1 + 4 + 4^2 + ... + 4^6, ta có thể sử dụng công thức tổng của cấp số nhân:
S = (a * (r^n - 1)) / (r - 1)
Trong đó:
- a là số hạng đầu tiên của dãy (a = 1)
- r là công bội của dãy (r = 4)
- n là số lượng số hạng trong dãy (n = 6)
Áp dụng vào bài toán, ta có:
S = (1 * (4^6 - 1)) / (4 - 1)
= (4^6 - 1) / 3
Để chứng minh A = {(4^7 - 1) : 3}, ta cần chứng minh rằng S = (4^7 - 1) : 3.
Ta có:
(4^7 - 1) : 3 = (4^7 - 1) / 3
Để chứng minh hai biểu thức trên bằng nhau, ta sẽ chứng minh rằng (4^7 - 1) / 3 = (4^6 - 1) / 3.
Ta có:
(4^7 - 1) / 3 = (4^6 * 4 - 1) / 3
= (4^6 * 4 - 1 * 4^0) / 3
= (4^6 * 4 - 4^6) / 3
= 4^6 * (4 - 1) / 3
= (4^6 - 1) / 3
Vậy ta đã chứng minh được A = {(4^7 - 1) : 3}.
K
2
25 tháng 1 2016
=> a +b - a . b = 0
a ( b - 1 ) - ( b - 1 ) = 1
( a - 1 ) ( b - 1 ) = 1 = 1 . 1 = - 1 . ( - 1 )
=> a - 1 = 1 va b - 1 =1
hoac a - 1 = - 1 va b - 1 = - 1
( Con lai tu lm nha )
**** nha !!
PT
8 tháng 5 2016
hello my name is science, 6d grade intelligent, intelligent 12-year-old middle school thcs bar, tea and shakes his loyal py in Thai Nguyen
on every morning I usually teach from 6 hours, then go get dressed, brush your teeth, wash your face, then eat breakfast, go to school. Afternoon often helps her parents with housework and homework, his hobby is eating fried chicken, cake, and then go out with their parents. on his summer days often parents for a swim, go fishing there like her very often at his winter home and go to bed very early, I like to play sports as jumping rope, badminton, confused .
8 tháng 5 2016
hello my name is science , 6d grade intelligent , intelligent 12 -year-old middle school thcs bar , tea and shakes his loyal py in Thai Nguyen on every morning I usually teach from 6 hours , then go get dressed , brush your teeth , wash your face , then eat breakfast , go to school . Afternoon often helps her parents with housework and homework, his hobby is eating fried chicken , cake , and then go out with their parents. on his summer days often parents for a swim , go fishing there like her very often at his winter home and go to bed very early, I like to play sports as jumping rope , badminton , confused .
NV
Nguyễn Việt Lâm
Giáo viên
23 tháng 12 2022
Nửa chu vi mảnh vườn là:
\(96,8:2=48,4\left(m\right)\)
Chiều dài mảnh vườn là:
\(\left(48,4+5,4\right):2=26,9\left(m\right)\)
Chiều rộng mảnh vườn là:
\(\left(48,4-5,4\right):2=21,5\left(m\right)\)
Diện tích mảnh vườn là:
\(26,9\times21,5=578,35\left(m^2\right)\)
20 tháng 10 2017
\(\left|x\right|+13=20\)
\(\Rightarrow\left|x\right|=20-13\)
\(\Rightarrow\left|x\right|=7\)
\(\Rightarrow\orbr{\begin{cases}x=7\\x=-7\end{cases}}\)
8 tháng 8 2023
program TICHSO;
var
n, i, j, maxVal, a_i, a_j: Integer;
begin
maxVal := 0;
Readln(n);
for i := 1 to n do
begin
Read(a_i);
if Abs(a_i) > maxVal then
maxVal := Abs(a_i);
end;
for i := 1 to n-1 do
begin
for j := i+1 to n do
begin
a_i := Abs(a[i]);
a_j := Abs(a[j]);
if (a_i * a_j) > maxVal then
maxVal := a_i * a_j;
end;
end;
Writeln(maxVal);
end.
5 tháng 9 2023
1: 60=2^2*3*5
280=2^3*5*7
=>BCNN(60;280)=2^3*5*7*3=840
2: 84=2^2*3*7
108=2^2*3^3
=>BCNN(84;108)=2^2*3^3*7=756
3: 13=13
15=3*5
=>BCNN(13;15)=13*3*5=195
4: 10=2*5
12=2^2*3
15=3*5
=>BCNN(10;12;15)=2^2*3*5=60
5: 8=2^3; 9=3^2; 11=11
=>BCNN(8;9;11)=2^3*3^2*11=72*11=792
6: 24=2^3*3
40=2^3*5
168=2^3*3*7
=>BCNN(24;40;168)=2^3*3*5*7=840
7: 30=2*3*5
105=3*5*7
=>BCNN(30;105)=2*3*5*7=210
8: 40=2^3*5
28=2^2*7
140=2^2*5*7
=>BCNN(40;28;140)=2^3*5*7=240
10: 16=2^4
25=5^2
=>BCNN(16;25)=2^4*5^2=400
Exercise 23)
19. Phone -> phoning
20. Do -> doing
21. Watch -> watching
22. To go -> going
23. To listening -> listening
24. Save -> saving
25. To protect -> protecting
26. Get -> getting
27. Hear -> hearing
28. Receive -> receiving
29. Meet -> meeting
30. Buy -> buying
31. Watch -> watching
32. Play -> playing
33. Wash -> washing
34. Learn -> learning
35. To sing -> sing
36. To smoke -> smoke
37. Working -> work
38. Doing -> do
39. Telling -> tell
40. Eating -> eat
41. Skipping -> skip
42. Catching -> catch
43. Watching -> watch
44. To go -> go
45. Listening -> listen
46. To save -> save
47. To protect -> protect
48. To prepare -> prepare
Exercise 24)
1. She needs to buy a new house.
2. I would like to drink white coffee.
3. Would you like to go to the cinema with me tonight :>>?
4. She is able to speak English well
5. I’m delighted to get good marks.
6. It takes me two hours to go jogging every day.
7. My father always asks me not to stay up late.
8. Don’t forget to turn off the dripping faucet.
9, Remember to phone me at 6 o’clock tonight.
10. In Viet Nam, people enjoy reading newspapers and magazines.
11. She enjoys drinking milk.
12. Would you mind closing the door?
13. Do you mind helping me to do this exercise?
14. What about playing tennis?
15. How about watching the newsreel on TV
16. We suggest saving energy.
17. We suggest protecting our environment.
18. I suggest putting garbage bins around the schoolyard.
19. We’re all looking forward to hearing from you soon.
20. I’m looking forward to receiving your letter.
21. I look forward to meeting you soon
22. How many hours a day do you spend doing homework?
23. I am interested in reading novels.
24. Let’s go to a picnic this weekend.
25. Shall we listen to music tonight?
26. Why not we take part in these cultural activities?
27. Why not we save energy?
29. Why not we protect our environment.
30. How about using public buses instead of motorbikes to reduce exhaust fume?
Chúc cậu hc tốt nha =)