A=9/1.2+9/2.3+...+9/2020.2021+9/2021.2022
giup minh luon voi
S=(1-2/2.3)(1-2/3.4)...(1-2/2020.2021)
Tính
a) S= 1.2+2.3+3.4+...+32.33
b) S= 1.2+2.3+3.4+...+49.50
Tính nhanh
C=1.2+2.3+3.4+...+2014.2015
K=1.2+2.3+3.4+..+(n-1).n
A=1.2+2.3+3.4+...+99.100
Tính các biểu thức sau:
C=1.2+2.3+3.4+...+98.99
D=(1.99+2.99+3.99+...99.99)-(1.2+2.3+3.4+...98.99
cho A = 1/1.2+1/2.3+1/3.4+...+1/49.50 ; cho B = 1.2+1.3+3.4+....+49.50
tính 50mủ 2A - B/17
A = 1.2+2.3+3.4+.........................+1999.2000
A=1.2+2.3+3.4+...+123.124= ?