Question

tinh

A=2^100 -2^99+2^98-2^97+ ...+2^2

 

Answer 1

\(A=2^{100}-2^{99}+2^{98}-2^{97}+..+2^2-2\)

\(\Rightarrow2A=2^{101}-2^{100}+2^{99}-2^{98}+..+2^3-2^2\)

\(\Rightarrow2A+A=2^{101}-2\Rightarrow3A=2^{101}-2\Rightarrow A=\frac{2^{101}-2}{3}\)

Answer 2

moi hok lop 6

Answer 3

ở cuối còn thiếu,2^2-2 ms làm đc