mik tính mt ra 2047 k bjt có đúng k nữa
A= 1+22 + 22 + 23 +.....+ 210
A= (2^11 -1)/(2-1)
A= 2047
\(A=1+2+2^2+...+2^{10}\)
\(2A=2\times\left(1+2+2^2+...+2^{10}\right)\)
\(2A=2+2^2+2^3+...+2^{11}\)
\(\Rightarrow A=2A-A=\left(2+2^2+2^3+...+2^{11}\right)-\left(1+2+2^2+...+2^{10}\right)\)
\(A=2^{11-1}\)
\(A=2017\)
A=1+2+22+23+24+..+210
=>2A=2(1+2+22+23+24+..+210)
=>2A=2+22+23+24+25+...+211
=>2A - A=(2+22+23+24+25+...+211) - (1+2+22+23+24+..+210)
=>A=211-1
=>A=2047
A = 1 + 22 + 23 + 24 + ... + 210
2A = 2 + 23 + 24 + 25 + ... + 210
2A - A = (2 + 23 + 24 + 25 + ... + 211) - (1 + 22 + 23 + 24 + ... + 210)
A = 2 + 210 - 1 - 4
= 210 - 3
=> 207
Vậy kết quả : 207
![[ Hải Vân ]](https://hoc24.vn/images/avt/avt2984407_256by256.jpg)
Ta có: 2A=2+2²+2³+2⁴+....+2¹¹
=>2A-A=(2+2²+2³+2⁴+....+2¹¹)-(1+2+2²+2³+....+2^10)
=>A=2¹¹-1
=2048-1
=2047
Hok tốt
\(A=1+2+2^2+\cdot\cdot\cdot+2^{10}\)
\(\Rightarrow2A=2+2^2+2^3+\cdot\cdot\cdot+2^{11}\)
\(\Rightarrow2A-A=\left(2+\cdot\cdot\cdot+2^{11}\right)-\left(1+\cdot\cdot\cdot+2^{10}\right)\)
\(\Rightarrow A=2^{11}-1\)
