Question

1.Rút gọn: B=(-5)^0+(-5)^1+(-5)^2+(-5)^3+...+(-5)^2017

Answer 1

\(B=\left(-5\right)^0+\left(-5\right)^1+\left(-5\right)^2+\left(-5\right)^3+...+\left(-5\right)^{2017}\)

\(\Leftrightarrow-5B=\left(-5\right)^1+\left(-5\right)^2+\left(-5\right)^3+\left(-5\right)^4+...+\left(-5\right)^{2018}\)

\(\Leftrightarrow-5B-B=\left(-5\right)^{2018}-\left(-5\right)^0\)

\(\Leftrightarrow-6B=\left(-5\right)^{2018}-1\)

\(\Leftrightarrow B=\frac{\left(-5\right)^{2018}-1}{-6}\)

Answer 2

Bạn ơi vì sao ở dòng 3 lại là (-5)^2017 - (-5)^0 vậy??