\(B=\left(-5\right)^0+\left(-5\right)^1+\left(-5\right)^2+...+\left(-5\right)^{2017}\)
\(-5B=\left(-5\right)^1+\left(-5\right)^2+\left(-5\right)^3+...+\left(-5\right)^{2017}\)
\(-6B=\left(-5\right)^{2017}-1\)
\(B=\frac{\left(-5\right)^{2017}-1}{-6}\)
Ta có : B = (-5)^0 + (-5)^1 + ......+ (-5)^2017
(-5)B = (-5)^1 + (-5)^2 + .......+ (-5)^2018
(-4)B = (-5)^0- (-5)^2018
B = 1 - (-5)^2018 / (-4)
Nếu có sai sót gì mong các bạn bỏ qua
\(-5B=\left(-5\right)^1+\left(-5\right)^2+...+\left(-5\right)^{2018}\)
\(-4B=\left(-5\right)^{2018}-\left(-5\right)^0\)
\(\Rightarrow B=\frac{\left(-5\right)^{2018}-\left(-5\right)^0}{-4}\)
\(B=\left(-5\right)^0+\left(-5\right)^1+................+\left(-5\right)^{2016}+\left(-5\right)^{2017}\)
\(\Rightarrow\left(-5\right)B=\left(-5\right)^1+\left(-5\right)^2+.............+\left(-5\right)^{2017}+\left(-5\right)^{2018}\)
\(\Rightarrow\left(-5\right)B-B=\left[\left(-5\right)^1+\left(-5\right)^2+..........+\left(-5\right)^{2018}\right]\)\(-\left[\left(-5\right)^0+\left(-5\right)^1+..........+\left(-5\right)^{2017}\right]\)
\(\Rightarrow\left(-6\right)B=\left(-5\right)^{2018}-\left(-5\right)^0\)
\(\Rightarrow B=\frac{\left(-5\right)^{2018}-\left(-5\right)^0}{\left(-6\right)}\)
Chúc bn học tốt