Question

Giải hộ mik bài 6,7,9

Answer 1

Bài 6 :

Ta có :

\(C=\)\(\dfrac{1}{7}+\dfrac{1}{8}+\dfrac{1}{9}+\dfrac{1}{10}+\dfrac{1}{11}+\dfrac{1}{12}+\dfrac{1}{14}+\dfrac{1}{15}+\dfrac{1}{18}+\dfrac{1}{22}+\dfrac{1}{24}+\dfrac{1}{28}+\dfrac{1}{33}\) \(C=\left(\dfrac{1}{7}+\dfrac{1}{14}+\dfrac{1}{28}\right)+\left(\dfrac{1}{8}+\dfrac{1}{12}+\dfrac{1}{24}\right)+\left(\dfrac{1}{9}+\dfrac{1}{18}\right)+\left(\dfrac{1}{10}+\dfrac{1}{15}\right)+\left(\dfrac{1}{11}+\dfrac{1}{22}+\dfrac{1}{33}\right)\)

Từ đây quy đồng lên ta sẽ có :

\(C=\dfrac{1}{4}+\dfrac{1}{4}+\dfrac{1}{6}+\dfrac{1}{6}+\dfrac{1}{6}\)

\(C=\dfrac{1}{2}+\dfrac{1}{2}\)

\(\Rightarrow C=1\)