Question

Chứng tỏ rằng : 3 + 3² + 3³ + .... + 3⁹⁹ + 3¹⁰⁰ chia hết cho 4 

Answer 1

=3+3^2+3^3+....+3^99+3^100

=(3+3^2)+(3^3+3^4)+(3^5+3^6)+...+(3^99+3^100)

=(1+3).3+(1+3).3^3.(1+3).3^5...(1+3).2^99

=4.3+4.3^3+4.3^5...4.2^99

Vậy,3+3^2+3^3+...+3^99+3^100 chia hết cho 4

Answer 2

=3+3^2+3^3+....+3^99+3^100

=(3+3^2)+(3^3+3^4)+(3^5+3^6)+...+(3^99+3^100)

=(1+3).3+(1+3).3^3. (1+3).3^5...(1+3).2^99

=4 . 3 + 4 . 3^3 + 4 . 3^5...4.2^99

Vậy:3 + 3^2 + 3^3 +...+ 3^99 +3^100 chia hết cho 4

Answer 3

Bài này cũng thuộc dạng khó đó nha!