\(C=1.2.3+2.3.4+...+48.49.50\)
\(\Rightarrow4C=1.2.3.4+2.3.4.4+...+48.49.50.4\)
\(=1.2.3.4+2.3.4.\left(5-1\right)+...+48.49.50.\left(51-47\right)\)
\(=1.2.3.4+2.3.4.5-1.2.3.4+...+48.49.50.51-47.48.49.50\)
\(=48.49.50.51\)
\(\Rightarrow C=\frac{48.49.50.51}{4}=1499400\)
c = 1.2.3+2.3.4+3.4.5+...+48.49.50 = ?
F= 1.2.3+2.3.4+3.4.5+......+ 48.49.50
Tinh A=1.2.3+2.3.4+3.4.5+...+48.49.50
P = 1/1.2.3 + 1/2.3.4 + 1/3.4.5 +...+ 1/n(n+1)(n+2)
S = 1/1.2.3 + 1/2.3.4 + 1/3.4.5 +...+ 1/48.49.50 .
1.2.3+2.3.4+3.4.5+........48.49.50
tính tổng
Tinh nhanh
A= \(1.2.3+2.3.4+3.4.5+...+48.49.50\)
B = \(1.2.3+2.3.4+3.4.5+...+n.\left(n+1\right).\left(n+2\right)\)
1.2.3+2.3.4+3.4.5+.......48.49.50
tính tổng các dãy số đó
Tìm S = 1.2.3+2.3.4+3.4.5+......+98.99.100
Mn giúp mk vs!!!
A=1.2+2.3+3.4+4.5+...1999.2000
B=1.1+2.2+3.3+4.4+....1999.1999
C=1.2.3+2.3.4+3.4.5+....+48.49.50
