Question

Bài 1:

36/21-15/20

63/45-20/25

Bài 2: Tính bằng cách thuận tiện nhất

3/5+3/16+13/16

 

Answer 1

Bài 1:
\(\dfrac{36}{21}-\dfrac{15}{20}\)
\(=\dfrac{12}{7}-\dfrac{3}{4}\)
\(=\dfrac{48}{28}-\dfrac{21}{28}\)
\(=\dfrac{27}{28}\)
\(----\)
\(\dfrac{63}{45}-\dfrac{20}{25}\)
\(=\dfrac{63}{45}-\dfrac{4}{5}\)
\(=\dfrac{63}{45}-\dfrac{36}{45}\)
\(=\dfrac{27}{45}=\dfrac{3}{5}\)
Bài 2:
\(\dfrac{3}{5}+\dfrac{3}{16}+\dfrac{13}{16}\)
\(=\dfrac{3}{5}+\left(\dfrac{3}{16}+\dfrac{13}{16}\right)\)
\(=\dfrac{3}{5}+1\)
\(=\dfrac{3}{5}+\dfrac{5}{5}\)
\(=\dfrac{8}{5}\)

Answer 2

`36/21-15/20`

`=12/7-3/4`

`=48/28-21/28`

`=27/28`

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`63/45-20/25`

`=7/5-4/5`

`=3/5`

__

`2)`

`3/5+3/16+13/16`

`=3/5+(3/16+13/16)`

`=3/5+16/16`

`=3/5+1`

`=3/5+5/5`

`=8/5`

`#QiN`