Question

Bài 1, trang 11 sgk lớp 5

1. Tính :

a. 3/10 × 4/9

6/5 : 3/7

3/4 × 2/5

5/8 : 1/2

b. 4 × 3/8

3 : 1/2

1/2 : 3

-Nêu cách trình bày dùm lun ạ !

 

Answer 1

b)\(4\times\dfrac{3}{8}=\dfrac{12}{8}=\dfrac{3}{2}\)

    \(3:\dfrac{1}{2}\) 

   =\(3\times\dfrac{2}{1}\)

  =  6   

  =\(\dfrac{1}{2}:3\)

  = \(\dfrac{1}{2}\times\dfrac{1}{3}\)

  = \(\dfrac{1}{6}\)

 

Answer 2

1a, \(\dfrac{3}{10}\) \(\times\) \(\dfrac{4}{9}\) 

= \(\dfrac{3\times2\times2}{2\times5\times3\times3}\) 

= \(\dfrac{2}{15}\)

\(\dfrac{6}{5}\): \(\dfrac{3}{7}\)

= \(\dfrac{6}{5}\) \(\times\) \(\dfrac{7}{3}\)

= \(\dfrac{14}{5}\)

\(\dfrac{3}{4}\) \(\times\) \(\dfrac{2}{5}\)

= \(\dfrac{3\times2}{2\times2\times5}\)

= \(\dfrac{3}{10}\)

\(\dfrac{5}{8}\) : \(\dfrac{1}{2}\)

= \(\dfrac{5}{8}\) \(\times\) \(\dfrac{2}{1}\)

= \(\dfrac{5}{4}\)