\(A=2^{100}-2^{99}+2^{98}-2^{97}+...+2^2-2\)
\(\Rightarrow2A=2^{101}-2^{100}+2^{99}-2^{98}+...+2^3-2^2\)
\(\Rightarrow2A+A=2^{101}-2^{100}+2^{99}-2^{98}+...+2^3-2^2+2^{100}-2^{99}-2^{98}-2^{97}+...+2^2-2\)
\(\Rightarrow3A=2^{201}-2\)
\(\Rightarrow\)\(\frac{2^{201}-2}{3}\)
mình lấy cả 2 nick tích cho nguyên linh đấy
\(2A=2^{101}-2^{100}+...+2^3-2^2\)
\(A=2^{100}-2^{99}+...+2^2-2\)
\(\Rightarrow3A=2A+A=2^{101}-2\)
\(\Rightarrow A=\frac{2^{101}-2}{3}\)
được của ló