Question

Tìm x biết \(\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\right):x=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}\)

 

Answer 1

\(\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\right):x=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}\)

\(\Rightarrow\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{8}+\frac{1}{8}-\frac{1}{16}\right):x=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}\)

\(\Rightarrow\left(1-\frac{1}{16}\right):x=1-\frac{1}{5}\)

\(\Rightarrow\frac{15}{16}:x=\frac{4}{5}\)

\(\Rightarrow x=\frac{15}{16}:\frac{4}{5}=1\frac{11}{64}\)

Answer 2

Ớ ! Mới thấy đề bài là 2 số hạng 1/20 cơ mà ????