@Yogile
Đáp án:
=$\dfrac{49}{100}$
Giải thích các bước giải:
$\dfrac{1}{2.3}+\dfrac{1}{3.4}+\dfrac{1}{4.5}+...+\dfrac{1}{98.99}+\dfrac{1}{99.100}\\$
=$(\dfrac{1}{2}-\dfrac{1}{3})+(\dfrac{1}{3}-\dfrac{1}{4})+(\dfrac{1}{4}-\dfrac{1}{5})+...+(\dfrac{1}{98}-\dfrac{1}{99})+(\dfrac{1}{99}-\dfrac{1}{100})\\$
=$\dfrac{1}{2}-\dfrac{1}{100}\\$
=$\dfrac{50}{100}-\dfrac{1}{100}\\$
=$\dfrac{49}{100}$
