Question

[phong2k12]

b = 5/2 x 6 + 5,6 x 10 + ...+ 5/402 x 406

Answer 1

[Nguyễn Thị Thương Hoài]

B = \(\dfrac{5}{2.6}\)+ \(\dfrac{5}{6.10}\)+...+\(\dfrac{5}{402.406}\)

B = 5.( \(\dfrac{1}{2.6}\)+ \(\dfrac{1}{6.10}\)+...+\(\dfrac{1}{402.406}\))

B = 5.(\(\dfrac{1}{2}\) - \(\dfrac{1}{6}\)+ \(\dfrac{1}{6}\)- \(\dfrac{1}{10}\)+...+\(\dfrac{1}{402}\)-\(\dfrac{1}{406}\))

B = 5.(\(\dfrac{1}{2}\) - \(\dfrac{1}{406}\))

B = 5.\(\dfrac{101}{203}\)

B = \(\dfrac{505}{203}\)