Question

Bài 1: Tính bằng 2 cách

a) (2/3 x 4/5) x 5/6

b) (1/2 + 1/3) x 1/5

 

Answer 1

`( 2/3 xx 4/5) xx 5/6`

`= 8/15 xx 5/6`

`= 40/90`

`=4/9`

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`( 2/3 xx 4/5) xx 5/6`

`= 2/3 xx (4/5 xx 5/6)`

`= 2/3 xx 2/3`

`= 4/9`

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`(1/2 + 1/3) xx 1/5`

`= ( 3/6 +2/6) xx 1/5`

`= 5/6 xx1/5`

`= 5/30`

`=1/6`

__

`(1/2 + 1/3) xx 1/5`

`=1/2 xx 1/5 + 1/3 xx 1/5`

`= 1/10 + 1/15`

`=1/6`

Answer 2

a)

c1

`(2/3xx4/5)xx5/6`

`=8/15xx5/6`

`=4/9`

c2

`(2/3xx4/5)xx5/6`

`=2/3xx4/5xx5/6`

`=2/3xx5/6xx4/5`

`=5/9xx4/5`

`=4/9`

b)

c1

`(1/2+1/3)xx1/5`

`=(3/6+2/6)xx1/5`

`=5/6xx1/5`

`=1/6`

c2

`(1/2+1/3)xx1/5`

`=1/2xx1/5+1/3xx1/5`

`=1/10+1/15`

`=3/30+2/30`

`=5/30=1/6`