Question

[Nguyễn Quỳnh Trang]

A=\(\dfrac{2}{1.4}+\dfrac{2}{4.7}+\dfrac{2}{7.9}+...+\dfrac{2}{73.76}\)

Hãy tính A

Answer 1

[Lê Phương Huệ]

Ta co:\(\)

\(A=\dfrac{2}{1.4}+\dfrac{2}{4.7}+.....+\dfrac{2}{73.76}\)

\(=>A=2.\left(\dfrac{1}{1.4}+\dfrac{1}{4.7}+....+\dfrac{1}{73.76}\right)\)

\(=>A=2.\left(1-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+....+\dfrac{1}{73}-\dfrac{1}{76}\right)\)

\(=>A=2.\left(1-\dfrac{1}{76}\right)\)

\(=>A=2.\dfrac{75}{76}=\dfrac{2.75}{2.38}\)

\(=>A=\dfrac{75}{38}\)

Tick cho mk nha

Answer 2

[Nguyễn Quỳnh Trang]

cảm ơn bạn nhé!