Tính A= 1+(1+2)+(1+2+3)+........+(1+2+3+.....+2017)/1.2+2.3+3.4+.......+2017.2018
Tính A=1+(1+2)+(1+2+3)+....+(1+2+3+.....+2017)/1.2+2.3+3.4+......+2017.2018
Tính nhanh
1.2 + 2.3 + 3.4 + 4.5 + ... + 2017.2018
tính các tổng sau:
A=1.2+2.3+3.4+...+n(n+1)
B=1.2.3+2.3.4+...+n(n+1)(n+2)
C=1.2+3.4+5.6+...+2017.2018
D=1.4+2.5+3.6+...+n(n+3)
Giúp mk nha, ai nhanh mk k!
S = 1/1.2 + 1/2.3 + 1/3.4 +..........1/2017.2018 + 1/2018.2019
can gap
TÍNH A=1.2^2 + 2.3^2 +..........................+2017.2018^2
Tính A = 1.2^2+2.3^2+3.4^2+....+2017.2018^2
(1.2+2.3+......+2017.2018+2018.2019)-(1 mũ2+2 mũ2+.......+2017 mũ2 +2018 mũ 2
a,1/1.2 + 1/2.3 + 1/ 3.4+....+ 1/2017.2018
b, 2/3.5+ 2/ 5.7 + 2/7.9 +....+ 2/.91.99
Ai giúp mink tích cho!
a)\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}\)
b)\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{2017.2018}\)
c)\(\frac{3}{2.5}+\frac{3}{5.8}+\frac{3}{8.11}+...+\frac{3}{2012.2015}\)