Đặt :

      A=1/5^2+1/6^2+...+1/100^2

Ta có:

A<1/4.5+1/5.6+...+1/99.100=1/4-1/5+1/5-1/6+...+1/99-1/100=1/4-1/100<1/4

Đúng thì k nha!

Ta có:

A>1/5.6+1/6.7+...+1/100.101=1/5-1/6+1/6-1/7+....+1/100+1/101>1/6

0,96 k minh nha, mac du ko chac chan lam nhung ma chac la vay