\(-\dfrac{1}{99}-\dfrac{1}{99.98}-\dfrac{1}{98.97}-\dfrac{1}{97.96}-...-\dfrac{1}{3.2}-\dfrac{1}{2.1}\)
\(=-\dfrac{1}{99}-\left(\dfrac{1}{98}-\dfrac{1}{99}\right)-\left(\dfrac{1}{97}-\dfrac{1}{98}\right)-\left(\dfrac{1}{96}-\dfrac{1}{97}\right)-...-\left(\dfrac{1}{2}-\dfrac{1}{3}\right)-\left(1-\dfrac{1}{2}\right)\)
\(=-\dfrac{1}{99}-\dfrac{1}{98}+\dfrac{1}{99}-\dfrac{1}{97}+\dfrac{1}{98}-\dfrac{1}{96}+\dfrac{1}{97}-...-\dfrac{1}{2}+\dfrac{1}{3}-1+\dfrac{1}{2}\)
\(=-1\)
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