Question

1/13*14+ 1/14*15+ 1/15*16+ ...+ 1/99*100
Помогите решить

Answer 1

$=\frac{1}{13}-\frac{1}{14} +\frac{1}{14} -...+\frac{1}{99} -\frac{1}{100} =\frac{1}{13} -\frac{1}{100}=\frac{100-13}{1300} =\frac{87}{1300}$