Question

Chứng minh rằng:

A=2+2^2+2^3+....+2^14+2^15 chia hết cho 7

Answer 1

A=(2+2^2+2^3)+...+(2^13+2^14+2^15)

=14+...+2^13X(2+2^2+2^3)

=14+...+2^13x14

=>A chia het cho 7

tick minh nha bai nay sang nay minh moi lam duoc 10

Answer 2

=2[+1+2+4]+2⁴[1+2+4].....+2¹³[1+2+4]

=2.7+2⁴.7+..+2^13.7

⁼[2+2⁴+2⁷+..+2¹³].7chia hết cho 7

 

Answer 3

A=(2+2^2+2^3)+(2^4+2^5+2^6)+....+(2^13+2^14+2^15)

A=2(1+2+2^2) + 2^4.(1+2+2^2)+...+2^13.(1+2+2^2)

A=2.7+ 2^4.7+ .......+ 2^13.7

A=7.(2+2^4+...+2^13) chia hết cho 7