Ta có:\(A=1+3+3^2+3^3+3^4+3^5\)

\(\Rightarrow2A=1+3^2+3^3+3^4+3^5+3^6\)

\(\Rightarrow2A+1=1+3^2+3^3+3^4+3^5+3^6\)+1

\(2A+1=2+3^2+3^3+3^4+3^5+3^6\)

Nhớ chọn cho mình nhé,mình sẽ ủng hộ cho

A = 1+ 3\(^2\) + \(3^3\)+ ....+ \(3^5\)

\(\Leftrightarrow\)3A = 3+ \(3^2\)+\(3^3\)+...+\(3^6\)

\(\Leftrightarrow\)3A _ A = (3 + \(3^2\)+....+\(3^6\)) _ (1+ 3 +... +\(3^5\))

\(\Leftrightarrow\)2A = \(3^6\) _ 1

\(\Leftrightarrow\)2A +1 = \(3^6\)( dạng lũy thừa bậc 6 )

\(3^4.3^3=3^{4+3}=3^7\)

Lũy thừa là tích của các số giống nhau

3⁴.3³

=3⁴⁺³

=3⁷

lũy thừa là số mũ

3⁴x3³=81x27=2187=3⁷

3A=3+3²+3³+....+3²⁰⁰⁸

2A=(3+3²+....+3²⁰⁰⁸)-(1+3+...+3²⁰⁰⁷)=3²⁰⁰⁸-1

3A=\(3+3^2+3^3+...+3^{11}\)

3A-A=(\(3+3^2+3^3+...+3^{11}\))-(\(1+3+3^2+...+3^{10}\))

2A=\(3^{11}-1\)

2A+1=\(3^{11}\)

lai sai

Thanks

\(A=1+3+3^2+...+3^{2007}\)

\(\Rightarrow3A=3+3^2+3^3+...+3^{2008}\)

\(\Rightarrow3A-A=\left(3+3^2+3^3+...+3^{2008}\right)-\left(1+3+3^2+...+3^{2007}\right)\)

\(\Rightarrow2A=3+3^2+3^3+...+3^{2008}-1-3-3^2-...-3^{2007}\)

\(\Rightarrow2A=3^{2008}-1\)

\(\Rightarrow2A+1=3^{2008}\)

\(A=1+3+3^2+...+3^{2007}\)

\(\Rightarrow3A=3+3^2+3^3+...+3^{2008}\)

\(\Rightarrow3A-A=\left(3+3^2+3^3+...+3^{2008}\right)-\left(1+3+3^2+...+3^{2007}\right)\)

\(\Rightarrow2A=3+3^2+3^3+...+3^{2008}-1-3-3^2-...-3^{2007}\)

\(\Rightarrow2A=3^{2008}-1\)

\(\Rightarrow2A+1=3^{2008}\)

Nhớ k cho mk nha!!!

1 + 2 + 3 + 4 + 5 + 6 = 21

21

k mik nha mik k lại cho

21 nha, r

1)= 6

2)=9

3)=6 nha bn! 

1)=6

2)=9

3)=6  k cho mik nha

1+1-1+5=5

2+1-3+9=9

3+1-2+4=6

21

k mik nha các bạn

\(1+2+3+4+5+6=?\)

                                            \(=\left(1+5\right)+\left(2+4\right)+\left(3+6\right)\)

                                            \(=6+6+9=21\)

=21 nha.

TK MK ĐI MK TK LẠI CHO