- Bài làm :

2/3+2/6+2/12+2/24+2/48+2/96+2/192

<=> 2 ( 1/3 + 1/6 + 1/ 12 + 1/24 + 1/48 + 1/96 + 1/192 )

<=> 2 ( 1/1.3 + 1/ 2.3 + 1/3.4 + 1/ 6.8 + 1/8.10 )

<=> 2/3 + 2 ( 1/2 - 1/4 ) + 2 ( 2/4.6 + 2/6.8 ) :2

<=> 2/3 + 1/2 + 1/8 + 1/23

<=> 127/96

#chucbanhoctot

@we are one

~NO COPY~ 

Chào bn nhé, chào mừng bn đến với Hoidap247 , tvm!!

A = $\frac{2}{3}$ + $\frac{2}{6}$ + $\frac{2}{12}$ + $\frac{2}{24}$ + $\frac{2}{48}$ + $\frac{2}{96}$ + $\frac{2}{192}$

⇒ 2A = $\frac{4}{3}$ + $\frac{2}{3}$ + $\frac{2}{6}$ + $\frac{2}{12}$ + $\frac{2}{24}$ + $\frac{2}{48}$ + $\frac{2}{96}$

⇒ 2A - A = ($\frac{4}{3}$ + $\frac{2}{3}$ + $\frac{2}{6}$ + $\frac{2}{12}$ + $\frac{2}{24}$ + $\frac{2}{48}$ + $\frac{2}{96}$) - ($\frac{2}{3}$ + $\frac{2}{6}$ + $\frac{2}{12}$ + $\frac{2}{24}$ + $\frac{2}{48}$ + $\frac{2}{96}$ + $\frac{2}{192}$)

⇒  A = $\frac{4}{3}$ + $\frac{2}{3}$ + $\frac{2}{6}$ + $\frac{2}{12}$ + $\frac{2}{24}$ + $\frac{2}{48}$ + $\frac{2}{96}$ - $\frac{2}{3}$ - $\frac{2}{6}$ - $\frac{2}{12}$ - $\frac{2}{24}$ - $\frac{2}{48}$ - $\frac{2}{96}$ - $\frac{2}{192}$

⇒  A = $\frac{4}{3}$ - $\frac{2}{192}$

⇒  A = $\frac{256}{192}$ - $\frac{2}{192}$

⇒  A = $\frac{254}{192}$ = $\frac{127}{96}$