\(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{8}+\frac{1}{8}-\frac{1}{16}+\frac{1}{16}-\frac{1}{32}+\frac{1}{32}\)
\(=1-\frac{1}{32}\)
\(=\frac{31}{32}\)
k mk nha
\(=\left(\frac{1}{2}+\begin{cases}1\\4\end{cases}+\frac{1}{8}\right)+\left(\frac{1}{16}+\frac{1}{32}\right)\\ =\frac{7}{8}+\frac{3}{32}\\ =\frac{31}{32}\)
Đặt S = 1/2 + 1/4 + 1/8 + 1/16 + 1/32
2.S = 1 + 1/2 + 1/4 + 1/8 + 1/16
2.S - S = ( 1 + 1/2 + 1/4 + 1/8 + 1/16 ) - ( 1/2 + 1/4 + 1/8 + 1/16 + 1/32 )
S = 1 - 1/32
S = 31/32
