Question

\(A=\frac{1}{3X5}+\frac{1}{5X7}+...+\frac{1}{47X49}+\frac{1}{49X51}\)

giải hộ mình nha

Answer 1

2A = 2/3x5 + 2/5x7 + ... + 2/47x49 + 2/49x51

2A = 1/3 - 1/5 + 1/5 - 1/7 + ... + 1/47 - 1/49 + 1/49 - 1/51

2A = 1/3 - 1/51

2A = 16/51

  A = 16/51 : 2 =8/51

Answer 2

A = 1/2 . ( 1/3 -1/5 + 1/5-1/7 + ...+1/47 - 1/49 + 1/49 - 1/51)

A = 1/2 .(1/3 -1/51)

A=1/2 . 16/51

A= 8/51

Answer 3

A=1/3.5+1/5.7+...+1/47.49+1/49.51

2A=2/3.5+2/5.7+...+2/47.49+2/49.51

2A=1/3-1/5+1/5-1/7+...+1/47-1/49+1/49-1/51

2A=1/3-1/51=48/153

=> A=48/153:2=8/51