Tính tổng : C = 1.3.5 + 3.5.7 + 5.7.9 + .... + 93.95.97 + 95.97.99
Tính C=1.3.5-3.5.7+5.7.9-7.9.11+...-97.99.101
Tính A = 1.3.5 + 3.5.7 + 5.7.9 + .... + 95.97.99 + 97.99.101
tính
A= 1/1.3.5+ 1/3.5.7+1/5.7.9+.....+1/95.97.99
tính
B=1.3.5+3.5.7+5.7.9+7.9.11+...+99.101.103
1.3.5+3.5.7+5.7.9+...+93.95.97+95.97.99
(.) là x
A= 1/1.3.5+ 1/3.5.7+1/5.7.9+.....+1/95.97.99
Tính tổng
a) 9+99+999+...+999999
b) 1+11+111+...+1111111
c)1.2 + 2.3+3.4+4.5+...+98.99
d) 1.3.5 + 3.5.7+5.7.9+...+95.97.99
Tính:
A= -1+2-3-4-5+6-7-8-9+...-2021+2023-2024
B=1.3.5+3.5.7+5.7.9+7.9.11+...+99.101.103
C=1.3+2.4+3.5+...+198.200