Question

[lê nguyễn hà phương]

C=\(\frac{3}{4.7}\)+\(\frac{3}{7.10}\)+\(\frac{3}{10.13}\)+.......+\(\frac{3}{73.76}\)

Answer 1

[Thám Tử THCS Nguyễn Hiếu]

C = 3/4.7 + 3/7.10 + 3/10.13 + ... + 3/73.76

=1/4 - 1/7 + 1/7 - 1/10 + 1/10 - 1/13 + ... + 1/73 - 1/76

=1/4 - 1/76

=18/76

Answer 2

[Nguyễn Hưng Phát]

\(C=\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+......+\frac{1}{73}-\frac{1}{76}\)

\(=\frac{1}{4}-\frac{1}{76}\)

\(=\frac{19}{76}-\frac{1}{76}\)

\(=\frac{18}{76}=\frac{9}{38}\)