b, `\frac{1}{99.97} -\frac{1}{97.95}-\frac{1}{95.93} -...-\frac{1}{5.3}-\frac{1}{3.1}`
`=\frac{1}{97.99}-(\frac{1}{1.3}+\frac{1}{3.5}+...+\frac{1}{95.97})`
`=\frac{1}{99.97}-\frac{1}{2}(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{95} -\frac{1}{97})`
`=\frac{1}{99.97}-\frac{1}{2}(1-\frac{1}{97})`
`=\frac{1}{99.97}-\frac{48}{97}`
`=\frac{-4751}{9603}`
Hok tốt^^