Question

tính hợp lý

1) 5 - ( 1997 - 2006 ) + 1997

2) 4567 + ( 1234 - 4567 ) - 4

3) 1579 - ( 53 + 1579 ) - (-53)

4) 2001 - 15 + 54 - 2001 - 54

Answer 1

`5 - ( 1997 - 2006 ) + 1997`

` =5 - 1997 - 2006 + 1997`

`= (-1997 + 1997) +2006 + 5`

`=0 + 2006 + 5`

`=2011`

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`4567 + ( 1234 - 4567 ) - 4`

`=4567 + 1234 - 4567 - 4

`=(4567-4567)+1234 - 4`

`=0 + 1234 - 4`

`=1230`

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`1579 - ( 53 + 1579 ) - (-53)`

`=1579 -53 - 1579 + 53`

`=(1579 - 1579) + (53 - 53)`

`=0 + 0`

`=0`

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`2001 - 15 + 54 - 2001 - 54`

`=(2001 -2001) + (54-54) - 15`

`=0 + 0 - 15`

`=0 - 15`

`=-15`

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`#H.J`