Question

A= 4²/1.3+4²/3.5+4²/5.8+....+4²/45.47.1-3-5-...-49/8

Mình cần gấp lắm

Answer 1

\(A=\dfrac{4^2}{1.3}+\dfrac{4^2}{3.5}+\dfrac{4^2}{5.8}+...+\dfrac{4^2}{45.47}.\dfrac{1-3-5-...-49}{8}\)

\(A=4\left(\dfrac{4}{1.3}+\dfrac{4}{3.5}+\dfrac{4}{5.8}+...+\dfrac{4}{45.47}\right).\dfrac{1-3-5-...-49}{8}\)\(A=4\left[2\left(1-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{8}+...+\dfrac{1}{45}-\dfrac{1}{47}\right)\right].\dfrac{1-3-5-...-49}{8}\)\(A=8\left(1-\dfrac{1}{47}\right).\dfrac{1-3-5-...-49}{8}\)

\(A=8\left(1-\dfrac{1}{47}\right).\dfrac{-623}{8}\)

\(A=\dfrac{368}{47}.\dfrac{-623}{8}=\dfrac{-28658}{47}\)