A = 1 . 2 + 2 . 3 + 3 . 4 + ......... + 98 . 99 / 1 + ( 1 + 2 ) + ( 1 + 2 + 3 ) + ........... + ( 1 + 2 + 3 + ...... + 98 )
B = ( 1 / 51 . 52 ) + 1 / 52 . 53 + ...... + 1 / 100 . 101 ) : ( 1 / 1 . 2 + 1 / 2 . 3 + ........ + 1 / 99 . 100 + 1 / 100 . 101
(1/51+1/52+1/53+...+1/100)÷(1/1×2+1/3×4+1/4×5+...+1/99×100)
CMR(1/1*2+1/2*3+1/3*4+1/4*5+...+1/99*100):(1/51+1/52+1/53+...+1/100) = 1
1/51+1/52+1/53+...1/99+1/100 hay so sanh voi 1/2
Chứng tỏ A = 1/51 + 1/52 + 1/53 + .....+1/99 + 1/100 <1/2
chứng minh 1/2<1/51+1/52+1/53+.......+1/99+1/100<1
A= 1/51+1/52+1/53+...+1/99+1/100. so sánh với 1/2 và 1
Cho S=1/51+1/52+1/53+...+1/98+1/99+1/100. So sánh S với 1/2
1-1/2+1/3-1/4+1/5-1/6+.....+1/99-1/100=1/51+1/52+1/53+1/54+..+1/100
