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Lời giải:
$\text{VT}=(2^2-1)(2^2+1)(2^4+1)...(2^{1024}+1)$
$=(2^4-1)(2^4+1)....(2^{1024}+1)$
$=(2^8-1)(2^8+1)....(2^{1024}+1)$
$=(2^{1024})^2-1=2^{2048}-1$
$\text{VP}=1+2+...+2^{2047}$
$2\text{VP}=2+2^2+...+2^{2048}$
$\Rightarrow 2\text{VP}-\text{VP}=2^{2048}-1$
$\Leftrightarrow \text{VP}=2^{2048}-1$
Vậy $\text{VT}=\text{VP}$
Tìm x: \(\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{8}-\dfrac{1}{16} +...-\dfrac{1}{1024}=\dfrac{x}{1024}\)
\(\dfrac{x}{1024}=\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{8}-\dfrac{1}{16}+...-\dfrac{1}{1024}\)
\(\dfrac{2x}{1024}=1-\dfrac{1}{2}+\dfrac{1}{4}-\dfrac{1}{8}+...-\dfrac{1}{512}\)
\(\Rightarrow\dfrac{x}{1024}+\dfrac{2x}{1024}=1-\dfrac{1}{1024}\)
\(\Rightarrow\dfrac{3x}{1024}=\dfrac{1023}{1024}\)
\(\Rightarrow3x=1023\)
\(\Rightarrow x=341\)
Lời giải:
$\frac{x}{1024}=\frac{1}{2}-\frac{1}{4}+\frac{1}{8}-\frac{1}{16}+...-\frac{1}{1024}$
$\frac{2x}{1024}=1-\frac{1}{2}+\frac{1}{4}-\frac{1}{8}+...-\frac{512}$
$\Rightarrow \frac{x}{1024}+\frac{2x}{1024}=1-\frac{1}{1024}$
$\frac{3x}{1024}=\frac{1023}{1024}$
$\Rightarrow 3x=1023$
$\Rightarrow x=341$
Đặt \(A=-1-\frac{1}{2}-\frac{1}{4}-\frac{1}{8}-...-\frac{1}{512}-\frac{1}{1024}\)
\(\Rightarrow2A=-2-1-\frac{1}{2}-\frac{1}{4}-...-\frac{1}{512}\)
\(\Rightarrow2A-A=-2+\frac{1}{1024}\)
\(A=-2+\frac{1}{1024}\)
= -1-1+1/2-1/2+1/4-1/4+1/8-...+1/512-1/1024
=-1-1-1/1024
=-2\(\dfrac{1}{1024}\)
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