L= 1x2+2x4+3x6+4x8+5x10/3x4+6x8+9x12+12x16+15x20. tìm L
tính nhanh
1x2+2x43x6+4x8+5x10/3x4+6x8+9x12+12x16+15x20
Tính nhanh E= 2x4+4x6+6x8+...+98x100
tính nhanh 4/2x4 + 4/4x6 + 4/6x8 + .... + 4/2008x 2010
A=2x4+4x6+6x8+....+98x100
S=2x4+4x6+6x8+...+98x100+100x102
tinh F=2x4+4x6+6x8+....+100x102
tinh F = 2x4+4x6+6x8+....+100x102
4/ 2x4 +4/4x6+4/6x8+.......+4/2008x2010