Question

A= 1/2.5 + 1/5.8 + 1/8.11 + .....+ 1/150.153

Answer 1

tham khảo ở đây nha

https://olm.vn/hoi-dap/detail/222956295982.html

Answer 2

\(A=\dfrac{1}{3}\left(\dfrac{1}{2}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{11}+...+\dfrac{1}{150}-\dfrac{1}{153}\right)\)

\(=\dfrac{1}{3}.\dfrac{151}{306}=\dfrac{151}{918}\)