Question

[Ngũ Huyền Thanh]

[1-1/2] x [1-1/3] x [ 1-1/4] x .......x [1-1/18] x [ 1-1/19] x [ 1-1/2-]

Answer 1

[Louis Pasteur]

\(\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right).........\left(1-\frac{1}{19}\right).\left(1-\frac{1}{20}\right)\)

\(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.\frac{4}{5}...........\frac{18}{19}.\frac{19}{20}=\frac{1.2.3.4.5........19}{2.3.4.5.6.7......20}=\frac{1}{20}\)