`1/(1.2.3) + 1/(2.3.4) +.....+ 1/(98.99.100)`
`2/(1.2.3) + 2/(2.3.4) + ...+ 2/(98.99.100)`
`1/(1.2) - 1/(2.3) + 1/(2.3) - 1/(3.4) + ... + 1/(98.99) - 1/(99.100)`
`1/(1.2) - 1/(99.100)`
`1/2 - 1/9900`
= `4949/9900`
Tính tổng :
S=\(\frac{1}{1x2x3}+\frac{1}{2x3x4}+...+\frac{1}{98x99x100}\)
Tính nhanh:
1/1x2x3 + 1/2x3x4 + 1/3x4x5 + ... + 1/98x99x100
Tính :
a) 1/1x2+1/2x3+1/3x4+1/4x5+1/5x6+.....+1
b)1/1x2x3+1/2x3x4+1/3x4x5+.....+1/98x99x100
Tính :
a) 1/1x2+1/2x3+1/3x4+1/4x5+1/5x6+.....+1
b)1/1x2x3+1/2x3x4+1/3x4x5+.....+1/98x99x100
1x2x3+2x3x4+3x4x5+...+98x99x100
Tính S=1x2x3+2x3x4+...+98x99x100
1x2x3+2x3x4+3x4x5+...+98x99x100
Tính tổng
1x2x3+2x3x4+3x4x5+...+98x99x100
Help me!!!
tinh
a)A=1x2+2x3+3x4+............+99x100
b)B=1x3+3x5+5x7+............97x99
c)C=1x2x3+2x3x4+..............98x99x100
