A= 1.3 + 2.4 + 3.5 +....+ 98.100
= 1(2+1) + 2.(3+1) + 3.(4+1) +...+ 98(99+1)
= 1.2 + 1 + 2.3 + 2 + 3.4 + 3+....+ 98.99 +98
= (1.2 + 2.3 + 3.4+....98.99) + (1+2+3+....+98)
=323400 + 4851=328251
1.3+2.4+3.5+...+97.99+98.100
G = 1.3 +2.4+3.5+......+97.99+98.100.
G= 1.3+2.4+3.5+....+97.99+98.100
Tính 1.3+2.4+3.5+...+97.99+98.100
1.3 + 2.4 + 3.5 + 4.6 +.........+ 97.99 + 98.100
tính nhanh:1.3+2.4+3.5+.....+97.99+98.100
1/1.3-1/2.4+1/3.5-1/4.6+...+1/97.99-1/98.100 = ?
1/1.3+1/2.4+1/3.5+....+1/97.99+1/98.100 <3/4
TÍNH: a. \(1.3+3.5+....+97.99\)
b.\(1.3+2.4+3.5+....+98.100\)
c.\(2.4+4.6+....+98.100\)
