Question

Tính nhanh: (Tất cả các số ở đây đều là hỗn số) 1 1/3 x 1 1/8. x 1 1/15. x 1 1/24 x.....x 1 1/120 x 1 1/143

Answer 1

\(=\dfrac{4}{3}\cdot\dfrac{9}{8}\cdot...\cdot\dfrac{144}{143}\)

\(=\dfrac{2}{1}\cdot\dfrac{2}{3}\cdot\dfrac{3}{2}\cdot\dfrac{3}{4}\cdot...\cdot\dfrac{12}{11}\cdot\dfrac{12}{13}\)

\(=\dfrac{2}{1}\cdot\dfrac{3}{2}\cdot...\cdot\dfrac{12}{11}\cdot\dfrac{2}{3}\cdot\dfrac{3}{4}\cdot...\cdot\dfrac{12}{13}\)

=12*2/13=24/13