A = 1/3 + 1/6 + 1/12 + 1/24 + 1/48 + 1/96 + 1/192
A x 2 = 2/3 - ( 1/3 + 1/6 + 1/12 + 1/24 +1/48 + 1/96 + 1/192 ) - 1/192
A x 2 = 2/3 - A - 1/92
A x 2 - A = 2/3 - 1/92
A = bạn tự tính nha mk đang vợi bạn thông cảm cho
1/3 + 1/6+1/12+1/24+1/48+1/96
= 2/3 – 1/3 + 1/3 – 1/6+1/6- 1/12+1/12- 1/24+1/24-1/48+1/48-1/96
=2/3_1/96
= 63/99
= 21/32
= 2x(1/3+1/6+1/12+1/24+1/48+1/96+1/192)
= 2x(1-1/3+1/3-1/6+1/6-1/12+1/12-1/24+1/24-1/48+1/48-1/96+1/96-1/192)
= 2x(1-1/192)
= 2x191/192
=382/192=191/96
= 2x(1/3+1/6+1/12+1/24+1/48+1/96+1/192)
= 2x(1-1/3+1/3-1/6+1/6-1/12+1/12-1/24+1/24-1/48+1/48-1/96+1/96-1/192)
= 2x(1-1/192)
= 2x191/192
=382/192=191/96
nhân a với 3 ta có 3A=1+1/2+1/4+1/8+1/16+1/32+1/64
=> 3A *2 =2+1+ 1/2+1/4+1/8+1/16+1/32
trừ 6A-3A=> 3A=2-1/64
A=127/192
= 2x(1/3+1/6+1/12+1/24+1/48+1/96+1/192)
= 2x(1-1/3+1/3-1/6+1/6-1/12+1/12-1/24+1/24-1/48+1/48-1/96+1/96-1/192)
= 2x(1-1/192)
= 2x191/192
=382/192=191/96
= 2x(1/3+1/6+1/12+1/24+1/48+1/96+1/192)
= 2x(1-1/3+1/3-1/6+1/6-1/12+1/12-1/24+1/24-1/48+1/48-1/96+1/96-1/192)
= 2x(1-1/192)
= 2x191/192
=382/192=191/96
= 2x(1/3+1/6+1/12+1/24+1/48+1/96+1/192)
= 2x(1-1/3+1/3-1/6+1/6-1/12+1/12-1/24+1/24-1/48+1/48-1/96+1/96-1/192)
= 2x(1-1/192)
= 2x191/192
=382/192=191/96
= 2x(1/3+1/6+1/12+1/24+1/48+1/96+1/192)
= 2x(1-1/3+1/3-1/6+1/6-1/12+1/12-1/24+1/24-1/48+1/48-1/96+1/96-1/192)
= 2x(1-1/192)
= 2x191/192
=382/192=191/96
= 2x(1/3+1/6+1/12+1/24+1/48+1/96+1/192)
= 2x(1-1/3+1/3-1/6+1/6-1/12+1/12-1/24+1/24-1/48+1/48-1/96+1/96-1/192)
= 2x(1-1/192)
= 2x191/192
=382/192=191/96