Ta có : 1/2.2 < 1/1.2
1/3.3 < 1/2.3
.
.
.
1/100.100<1/99.100
==> 1/2.2+1/3.3+...+1/100.100 < 1/1.2 + 1/2.3+....+1/99.100
=> A < 1-1/100
=> A<99/100<100/100=1
==> a<1
Chứng minh rằng : 1/2.2+1/3.3+...+1/100.100<1
Chứng minh rằng:
a) A= 1/ 2.2 + 1/3.3 + 1/4.4 +....+ 1/100.100 < 1
1/2.2+1/3.3+1/4.4+....+1/100.100<1
A=1+2.2!+3.3!+4.4!+...+100.100!
tinh : A = (1 - 1/2.2) . (1 - 1/3.3) . (1 - 1/4.4)...(1 -1/100.100)
Chung minh M<3/4
1/2.2/3.3/4. ... .99/100.100/101
tính tổng D=1+1.1!+2.2!+3.3!+...+100.100!
A=1!+2.2!+3.3!+...+100.100!
Nhanh giùm !!!
