Question

Cho S = 1 + 3 + 3² + 3³ + 3⁴ + ..... + 3⁹. Chứng tỏ S chia hết cho 4

Answer 1

\(S=1+3+3^2+3^3+...+3^8+3^9\)

\(=1+3+3^2\left(1+3\right)+...+3^8\left(1+3\right)\)

\(=4\left(1+3^2+...+3^8\right)⋮4\)

Answer 2

\(S=\left(1+3\right)+3^2\left(1+3\right)+...+3^8\left(1+3\right)=4\left(1+3^2+...+3^8\right)⋮4\)

Answer 3

cảm ơn các bạn

 

Answer 4

Cho S = 1 + 3 + 3² + 3³ + 3⁴ + ..... + 3⁹. Chứng tỏ S chia hết cho 4

=>S= (1 + 3) + (3² + 3³) + (3⁴ +3⁵)+ ..... +(3⁸+ 3⁹)⋮4

=>S=4+36+324+3916+26244⋮4

S=30504⋮4

Answer 5