Question

Bài 9. Tính bằng cách thuận tiện:

21/16x 8/5x 15/7 =   ……..                           

 18/9 x 9/36x 27/3  =……………                                                

Answer 1

\(\dfrac{21}{16}\times\dfrac{8}{5}\times\dfrac{15}{7}=\dfrac{21\times8\times15}{16\times5\times7}=\dfrac{7\times3\times8\times5\times3}{8\times2\times5\times7}=\dfrac{3\times3}{2}=\dfrac{9}{2}\)

\(\dfrac{18}{9}\times\dfrac{9}{36}\times\dfrac{27}{3}=2\times\dfrac{1}{4}\times9=\dfrac{1}{2}\times9=\dfrac{9}{2}\)