Question

B1 : 2/3.5+2/5.7+2/7.9+...+2/41.43

Answer 1

Đặt biểu thức đó là : A = 2/3x5 + 2/5x7 + 2/7x9 + ... + 2/41x43

                              A = 2/3 - 2/5 + 2/5 - 2/7 + 2/7 - 2/9 + .... + 2/41 - 2/43

                              A = 2/3 - 2/43 

                             A = 80/129

Answer 2

\(=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{41}-\frac{1}{43}\)

\(=\frac{1}{3}-\frac{1}{43}\)

\(=\frac{40}{129}\)

Answer 3

NKT_Anime Hot Boy:sai lè lưỡi :D

Answer 4

40/129

Answer 5

\(=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{41}-\frac{1}{43}\)

\(=\frac{1}{3}-\frac{1}{43}\)

\(=\frac{40}{129}\)