Question

tính nhanh 

(123 + 345) + (456 -123) -[(2017-(-345)]

Answer 1

123+345+456-123-2017-345

= ( 123 - 123 ) + ( 345 - 345 ) - ( 123 + 2017 ) 

= 0 + 0 - 2140

= -2140

Answer 2

Trả lời :

( 123 + 345 ) + ( 456 - 123 ) - [ 2017 - ( - 345 ) ]

= 123 + 345 + 456 - 123 - 2017 - 345

= 123 + 345 + 456 + ( - 123 ) + ( - 2017 ) + ( - 345 )

= [ 123 + ( - 123 ) ] + [ 345 + ( - 345 ) ] + [ 456 + ( - 2017 ) ]

= 0 + 0 + ( - 1561 )

= - 1561

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