1/4x6 1/6x8 ... 1/298x300

Lời giải:

=\(\frac{1}{2}(\frac{2}{{2.4}} + \frac{2}{{4.6}} + \frac{2}{{6.8}} + ... + \frac{2}{{98.100}})\)

\( = \frac{1}{2}(\frac{1}{2} - \frac{1}{4} + \frac{1}{4} - \frac{1}{6} + \frac{1}{6} - \frac{1}{8} + ... + \frac{1}{{98}} - \frac{1}{{100}}) = \frac{1}{2}(\frac{1}{2} - \frac{1}{{100}}) = \frac{{49}}{{200}}\).