Question

Tính nhanh :

1/99 - 1/99.98 - 1/98.97 - 1/97.96 - ... - 1/3.2 - 1/2.1

Giúp mik vs 

Answer 1

\(\frac{1}{99}-\frac{1}{99.98}-\frac{1}{98.97}-\frac{1}{97.96}-...-\frac{1}{3.2}-\frac{1}{2.1}\)

\(=\frac{1}{99}-\left(\frac{1}{99.98}+\frac{1}{98.97}+\frac{1}{97.96}+...+\frac{1}{3.2}+\frac{1}{2.1}\right)\)

\(=\frac{1}{99}-\left(\frac{1}{99}-\frac{1}{98}+\frac{1}{98}-\frac{1}{97}+\frac{1}{97}-\frac{1}{96}+...+\frac{1}{3}-\frac{1}{2}+\frac{1}{2}-\frac{1}{1}\right)\)

\(=\frac{1}{99}-\left(\frac{1}{99}-1\right)=\frac{1}{99}-\frac{1}{99}+1=1\)

Answer 2

=1 nha bn, chắc vậy