Question

tính A=\(\frac{1}{6.10}+\frac{1}{10.14}+\frac{1}{14.18}+...+\frac{1}{402.406}\)

Answer 1

\(A=\frac{1}{6.10}+\frac{1}{10.14}+\frac{1}{14.18}+...+\frac{1}{402.406}\)

4\(A=\frac{1}{6}-\frac{1}{10}+\frac{1}{10}-\frac{1}{14}+\frac{1}{14}-\frac{1}{18}+...+\frac{1}{402}-\frac{1}{406}\)

4\(A=\frac{1}{6}-\frac{1}{406}\)

4\(A=\frac{100}{609}\)

\(\Rightarrow A=\frac{100}{609}:4\)\(=\frac{25}{609}\)

Answer 2

=1/6-1/10+1/10-1/14+1/14-1/18+...........+1/402-1/406

=1/6-1/406

Answer 3

=1/6-1/10+1/10-1/14+1/14-1/18+...+1/402-1/406

=1/6-1/406

Answer 4

bn ơi k cho mik đi bao giờ mik k cho kết qủa là 25/609