+ 2/6 + 2/3 + 2/12 2/24 + 2/48 + 2/96 + 2/192
= 2/3 x (1 + 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64)
Xét phần in Bracket: (1 +1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64)
1/2 + 1/4 = 1 1/4 -
1/2 + 1/4 + 1/8 = 1 - 1/8
1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 = 1 - 1/64 = 63/64
Suy ra 1 + 63/64 = 127/64
2/3 + 2/6 + 2/12 + 2/24 + 2/48 + 2/96 + 2/192
= 2/3 x 127/64 = 127/96