I didn't have a toothache and neither did they

ố táo ở  thùng thứ ba là :

    ( 77,9 - 26,74 ) : 2 = 25,58 ( kg )

               Đáp số : 25,58 kg táo

You shouldn't forget to write to your parents.

=> You'd better not to forget to write to your parents.

\(A=\frac{1}{7}+\frac{1}{91}+\frac{1}{247}+...+\frac{1}{1147}\)

\(A=\frac{1}{1.7}+\frac{1}{7.13}+\frac{1}{13.19}+....+\frac{1}{31.37}\)

\(A=\frac{6}{6}\left(\frac{1}{1.7}+\frac{1}{7.13}+\frac{1}{13.19}+...+\frac{1}{31.37}\right)\)

\(A=\frac{1}{6}\left(\frac{6}{1.7}+\frac{6}{7.13}+\frac{6}{13.19}+...+\frac{6}{31.37}\right)\)

\(A=\frac{1}{6}\left(1-\frac{1}{7}+\frac{1}{7}-\frac{1}{13}+\frac{1}{13}-\frac{1}{19}+....+\frac{1}{31}-\frac{1}{37}\right)\)

\(A=\frac{1}{6}\left(1-\frac{1}{37}\right)\)

\(A=\frac{1}{6}.\frac{36}{37}=\frac{6}{37}\)