Question

[hong pham]

Chứng Minh:\(\frac{1}{2^2}+\frac{1}{2^3}+\frac{1}{2^4}+....+\frac{1}{2^n}<1\)

Answer 1

[Le Thi Khanh Huyen]

Phung Viet Hoang sai rồi. VD: 1/2<1

Chẳng nhẽ 1/2+1/2<1

Answer 2

[An Trần Hà]

1/2^2 < 1/1.2

1/2^3 < 1/2.3

.....

1/2^n < 1/(n-1).n

=> 1/2^2 + 1/3^2 + ... + 1/n^2 < 1/1.2 + 1/2.3 + ... + 1/(n-1).n = 1 - 1/n <1.