Question

tính

A= 1/30 +1/42+1/56+1/72+1/90+1/110+1/132

Answer 1

=7/60

Answer 2

làm thế nào

Answer 3

Đ/s : 7/60 nha bn

k cho mình nhé maivananh

Answer 4

A=1/30+1/42+1/56+1/72+1/90+1/110+1/132

\(A=\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+...+\frac{1}{11.12}\)

\(A=\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+...+\frac{1}{11}-\frac{1}{12}\)

\(A=\frac{1}{5}-\frac{1}{12}\)

\(A=\frac{7}{60}\)