Câu hỏi của nam tran

Question

So sanh K=1/2+1/2²+1/2³ +......+1/2²⁰vơi H=1

Kudo Shinichi · Accepted Answer

$\Rightarrow$2K=$1+\frac{1}{2}+\frac{1}{2^2}+....+\frac{1}{2^{19}}$$\Rightarrow2K-k=k=1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{19}}-k$

$\Rightarrow k=1-\frac{1}{2^{20}}< 1$

$\Rightarrow k< H$

Vậy......

Câu trả lời:

$\Rightarrow$2K=$1+\frac{1}{2}+\frac{1}{2^2}+....+\frac{1}{2^{19}}$$\Rightarrow2K-k=k=1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{19}}-k$

$\Rightarrow k=1-\frac{1}{2^{20}}< 1$

$\Rightarrow k< H$

Vậy......