Question

tính :

\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{99.100}\)

 

Answer 1

Vì 2-1=1; 3-2=1; 4-3=1; ...

\(\Rightarrow=\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{99}-\frac{1}{100}\)

\(\Rightarrow=\frac{1}{1}-\frac{1}{100}\)

\(\Rightarrow=\frac{99}{100}\)

Answer 2

99/100 nha ban

chuc ban hoc gioi

Answer 3

đúng rồi