Question

m= 5^1 + 5^2 + 5^3 + ... + 5^49 + 5^50 a) chứng minh m chia hết cho 6      b)chứng minh m chia hết cho 30

Answer 1

`a, M = 5(1 + 5) + ... + 5^49( 1 + 5)`

`= (5 + 5^3 + ... + 5^49) . 6 vdots 6`

`b, M = 5 + 5^2 + 5^2(5 + 5^2) + ... + 5^48(5 + 5^2)`

`= 30 . (1 + 5^2 + ... + 5^48) vdots 30`

Answer 2

`a) M=5(1+5)+...+5^49 (1+5)`

`M=6.(5+5^3+...+5^49) ⋮ 6`

`b)` Theo câu `a`, ta có:

`M=6.5.(1+5^2+...+5^48) ⋮ 6xx5=30` (vì `(6,5)=1`)

Answer 3

a: \(M=5\left(1+5\right)+5^3\left(1+5\right)+...+5^{49}\left(1+5\right)\)

\(=6\cdot\left(5+5^3+...+5^{49}\right)⋮6\)

b: \(M=\left(5+5^2\right)+5^2\left(5+5^2\right)+...+5^{48}\left(5+5^2\right)\)

\(=30\left(1+5^2+...+5^{48}\right)⋮30\)