S=1x3+2x4+3x5+...........+99x101
tính : 1x3+2x4+3x5+.....+99x101+100x102
A=(1+1/1x3)x(1+1/2x4)x(1+1/3x5)x...x(1+1/99x101)
(1+1/1x3) x (1+1/2x4) x (1+1/3x5) x...x (1+1/99x101) x X = 100/101
1x3+3x5+5x7+...+99x101
Tính tổng :
A =5+10+15+ . . . . . + 2015+2020
B = 2/1x3 + 2/3x5 + 2/5x7 + . . . . . + 2/99x101
C = 1/2x4 + 1/4x6 + 1/6x8 + . . . . . + 1/98x100
Giải nhanh giúp mk nha ! ^.^
tính : 1x3 +3x5 +5x7 +....+99x101
tinh E=1x3+3x5+5x7+...+97x99+99x101
tinh E= 1x3+3x5+5x7+....+97x99+99x101