A= 1/1x2 + 1/2x3 + 1/3x4 + .........+1/99x100
Tinh : 1x2+2x3+3x4+...+99x100
tinh:
a,1/2x3 +1/3x4 + 1/4x5 +.....+1/99x100
1x2+2x3+3x4+...+98x99+99x100 = ?
1X2+2X3+3X4+..........+99X100+100X101
M=1x2+2x3+3x4+4x5+....+99x100
tinh 1/1x2+1/2x3+1/3x4...1/2005x2006
Tính tổng:
A = 1x2+3x4+4x5+...+99x100
B = 1x22+2x32+3x42+4x52+...+99x1002
Tính tổng: A = 1x2 + 2x3 + 3x4+...+99x100