ko bít

Đặt \(A=\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{1024}\)

\(2A=1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{1024}\)

\(2A-A=\left(1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{1024}\right)-\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{1024}\right)\)

\(\Rightarrow A=1-\frac{1}{1024}=\frac{1023}{1024}\)

Đặt \(A=\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+.....+\frac{1}{1024}\)

=> \(2A=1+\frac{1}{2}+\frac{1}{4}+.......+\frac{1}{512}\)

=> \(2A-A=1-\frac{1}{1024}\)

=> \(A=\frac{1023}{1024}\)

Giúp mình với! 

\(\dfrac{8}{3}\)=1\(\dfrac{5}{3}\)                         \(\dfrac{15}{6}\)=1\(\dfrac{9}{6}\)

\(\dfrac{85}{12}\)=7\(\dfrac{1}{12}\)                     \(\dfrac{5}{2}\)=1\(\dfrac{3}{2}\)

Chúc bạn học tốt.

\(\dfrac{8}{3}\rightarrow2\dfrac{2}{3}\)

\(\dfrac{15}{6}=\dfrac{5}{2}\rightarrow2\dfrac{1}{2}\)

\(\dfrac{85}{12}\rightarrow7\dfrac{1}{12}\)

\(\dfrac{5}{2}\rightarrow2\dfrac{1}{2}\)

\(\dfrac{8}{3}\Rightarrow2\dfrac{2}{3}\)        \(\dfrac{15}{6}=\dfrac{5}{2}\Rightarrow2\dfrac{1}{2}\)

\(\dfrac{85}{12}\Rightarrow7\dfrac{1}{12}\)     \(\dfrac{5}{2}\Rightarrow2\dfrac{1}{2}\)

nha bạn

6 How often does your grandfather often listen to the radio

7 How often do you go to the gym

8 What did they send

9 What time did he leave the party

10 Where did he go

11 Who did he meet for coffee

12 Why did she called the firemen

13 How did he go to school

14 What does lan like doing

15 Where was your father last months

16 How much is the dictionary

17 How long did it take to finish the composition

18 Who bought a poster

What did Mrs Robinson by

19 Where is a restaurant

20 What did her neighbor give her

21 How was the homework yesterday

22 Do you have magaazine and newspapers

23 How often do you go to the movies

Câu 4)

Có 3 dạng cơ năng

- thế năng hấp dẫn : quả bính đang bay 

- thế năng đần hồi : lò xo

- động năng : ô tô đang chạy

Câu 5)

Năng lượng vẫn đc bảo toàn và nó chỉ chuyển từ dạng này sang dạng khác

\(-2,5\times\left(x+\dfrac{1}{5}\right)=\dfrac{7}{5}\)

\(\Leftrightarrow x+\dfrac{1}{5}=\dfrac{7}{5}:\left(-2,5\right)\)

\(\Leftrightarrow x+\dfrac{1}{5}=\dfrac{7}{5}\times\left(-\dfrac{2}{5}\right)\)

\(\Leftrightarrow x+\dfrac{1}{5}=-\dfrac{14}{25}\)

\(\Leftrightarrow x=-\dfrac{19}{25}\)

\(-2,5\cdot\left(x+\dfrac{1}{5}\right)=\dfrac{7}{5}\)

\(x+\dfrac{1}{5}=\dfrac{7}{5}:\left(-2,5\right)\)

\(x+\dfrac{1}{5}=\dfrac{7}{5}\times\left(-\dfrac{2}{5}\right)\)

\(x+\dfrac{1}{5}=-\dfrac{14}{25}\)

\(x=-\dfrac{14}{25}-\dfrac{1}{5}\)

\(x=-\dfrac{19}{25}\)

x+1/5=7/5:(-5/2)
x= -14/25 -1/5
x= -19/25