A = \(\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{97.99}\)
2A = 2 . \(\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{97.99}\)
2A = \(\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{97.99}\)
2A = \(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{97}-\frac{1}{99}\)
2A = \(\frac{1}{3}-\frac{1}{99}\)
2A = \(\frac{32}{99}\)
A = \(\frac{32}{99}\div2\)
A =\(\frac{16}{99}\)
_HT_