Question

tính nhanh
( -2007)- (12 -2007)
g)
(28+ 39) +(168- 28 -39) 
h
(23- 145+ 59) -(23+ 59) 
i)
( -23)- (77- 1000) 
j)
(427 -2019) -(27 -2019)

Answer 1

oc cho

Answer 2

( -2007 ) - ( 12 - 2007 )

= -2007 - 12 + 2007

= ( -2007 + 2007 ) -12

= 0 -12

= -12

( 28 + 39 ) + ( 168 - 28 - 39 )

= 28 + 39 + 168 - 28 - 39

= ( 28 - 28 ) + ( 39 - 39 ) + 168

= 0 + 0 + 168

= 168

( 23 - 145 + 59 ) - ( 23 + 59 )

= 23 - 145 + 59 - 23 - 59

= ( 23 - 23 ) + ( 59 - 59 ) -145

= 0 + 0 - 145

= -145

( -23 ) - ( 77 + 1000 )

= -23 - 77 + 1000

= ( -23 -77 ) + 1000

= -1000 + 1000

= 0

( 427 - 2019 ) - ( 27 - 2019 )

= 427 - 2019 - 27 + 2019

= ( 427 - 27 ) - ( 2019 - 2019 )

= 400 - 0

= 400

Bạn k cho mk nha !!!