\(A=\dfrac{1}{5}+\dfrac{1}{10}+\dfrac{1}{20}+\dfrac{1}{40}+\dfrac{1}{80}+\dfrac{1}{160}\\ A=\dfrac{35}{160}+\dfrac{16}{160}+\dfrac{8}{160}+\dfrac{4}{160}+\dfrac{2}{160}+\dfrac{1}{160}\\ A=\dfrac{66}{160}\\ A=\dfrac{33}{80}.\)
`1/5 + 1/10 + 1/20+1/40+1/80 + 1/160=A`
`<=> (32+16+8+4+2+1)/160=A`
`<=> 63/160=A`
A=51+101+201+401+801+1601A=16035+16016+1608+1604+1602+1601A=16066A=8033.
Học tốt!!!