S=a^0+a^1+a^2+....+a^2007 (1) <=>a.S=a^1+a^2+a^3+....+a^2007+a^2008 (2) lấy (2) trừ (1) ta được: a.S-S=a^2008-a^0=a^2008-1 <=>S=(a^2008-1)/(a-1) với a=-1/7 ta có: S= (-1/7)^0 + (-1/7)^1+(-1/7)^2 +...+ (-1/7)^2007 =[(-1/7)^2008 -1]/(-1/7 -1)

Gọi tổng trên là A

\(\Leftrightarrow A=1+\left(-2\right)+2^2+...+2^{2014}+\left(-2\right)^{2015}\)

\(\Rightarrow2.A=2.1+\left(-2.2\right)+2.2^2+...+\left(-2.2\right)^{2015}\)

\(\Rightarrow2A=2+\left(-2\right)^2+2^3+...+\left(-2\right)^{2016}\)

\(\Leftrightarrow2A=2+2^2+2^3+...+2^{2016}\)

\(\Rightarrow2A-A=\left(2+2^2+2^3+...+2^{2016}\right)-\left[1+\left(-2\right)+2^3+...+\left(-2\right)^{2015}\right]\)\(\Rightarrow A=2^{2016}-1\)

Kho..................wa.....................troi.....................thi......................lanh.................ret.......................ai........................tich..........................ung.....................ho........................minh.....................cho....................do....................lanh

\(5654\)

de sai o mau so

NEU NHU MINH GIAI DC THI SAO K MINH KO THICH

\(b)\)

\(4n-3⋮3n-2\)

\(\Leftrightarrow3\left(4n-3\right)⋮3n-2\)

\(\Leftrightarrow12n-9⋮3n-2\)

\(\Leftrightarrow\left(12n-8\right)-1⋮3n-2\)

\(\Leftrightarrow4\left(3n-2\right)-1⋮3n-2\)

\(\Leftrightarrow1⋮3n-2\)

\(\Leftrightarrow3n-2\inƯ\left(1\right)=\left\{\pm1\right\}\)

\(\Rightarrow3n\in\left\{1;3\right\}\)

Mà: \(3n⋮3\)

\(\Leftrightarrow3n=3\)

\(\Leftrightarrow n=1\)

ta thay 31/2.32/2+60/2.59/2=1133

            33/2.34/2+58/2.57/2=1107

            ta co so hang:

            (60/2.59/2-31/2.32/2)/1+1=608 so

            so cap la :

                608/2=304 cap

            tong la :

               304.1133-(26.607)=328650

            no k cho minh nha

ta co q=5^58

         vay p<q