Question

Tìm x biết:

1/4.2/6.3/8.4/10......30/62.31/64=2^x

Answer 1

Trả lời 

\(\frac{1}{4}.\frac{2}{6}.\frac{3}{8}.\frac{4}{10}.....\frac{30}{62}.\frac{31}{64}=2^x\)

\(\Leftrightarrow\frac{1}{2.2.2....2.64}=2^x\) ( 30 số hạng 2 ) 

\(\Leftrightarrow\frac{1}{2^{30}.2^6}=2^x\)

\(\Leftrightarrow\frac{1}{2^{36}}=2^x\)

\(\Rightarrow2^x=2^{-36}\)

\(\Rightarrow x=-36\)

Vậy \(x=-36\)