Question

Answer 1

Giúp nhanh hộ tớ với ạ

Answer 2

a) \(Có:\) \(A=\left(1+2+2^2\right)+\left(2^3+2^4+2^5\right)+...+\left(2^{98}+2^{99}+2^{100}\right)\)

\(A=1.7+2^3.7+...+2^{98}.7\)

\(A=7\left(1+2^3+2^6+...+2^{98}\right)\)

\(\Rightarrow A⋮7\)

b) \(Có:\) \(B=1+3+3^2+...+3^{99}\)

\(B=\left(1+3\right)+\left(3^2+3^3\right)+...+\left(3^{98}+3^{99}\right)\)

\(B=1.4+3^2.4+...+3^{98}.4\)

\(B=4\left(1+3^2+...+3^{98}\right)\)

\(\Rightarrow B⋮4\)