Question

1.Tính hợp lí:

a)-[-345+1234-2014]-(345-1234)

b)(-31).47+(-31).52+(-31)

c)654+{374-[654-(+126)]

d)24.(16-5)-16.(24-5)

2.Tìm x;y ∈ Z biết

|x-8|+|y+2|=2

Answer 1

1.

a) -[ -345 + 1234 - 2014] - (345 - 1234)

= 345 - 1234 + 2014 - 345 + 1234

= ( 345 - 345) + ( -1234 +1234) +2014

= 0 + 0 + 2014 = 2014

b) ( -31) . 47 + ( -31) . 52 + ( -31)

= (-31) . ( 47 + 52 +1)

= (-31) . 100 = -3100

c) 654 +{ 374 - [ 654 - ( +126)]}

= 654 + [ 374 -( 654 - 126)]

= 654 + ( 374 - 654 + 126)

= 654 + 374 - 654 + 126

= ( 654 - 654 ) + ( 374 + 126 )

= 0 + 500 = 500

Answer 2

a) -[ -345 + 1234 - 2014] - (345 - 1234)

= 345 - 1234 + 2014 - 345 + 1234

= ( 345 - 345) + ( -1234 +1234) +2014

= 0 + 0 + 2014 = 2014

b) ( -31) . 47 + ( -31) . 52 + ( -31)

= (-31) . ( 47 + 52 +1)

= (-31) . 100 = -3100

c) 654 +{ 374 - [ 654 - ( +126)]}

= 654 + [ 374 -( 654 - 126)]

= 654 + ( 374 - 654 + 126)

= 654 + 374 - 654 + 126

= ( 654 - 654 ) + ( 374 + 126 )

= 0 + 500 = 500

Answer 3

a) -[ -345 + 1234 - 2014] - (345 - 1234)

= 345 - 1234 + 2014 - 345 + 1234

= ( 345 - 345) + ( -1234 +1234) +2014

= 0 + 0 + 2014 = 2014

b) ( -31) . 47 + ( -31) . 52 + ( -31)

= (-31) . ( 47 + 52 +1)

= (-31) . 100 = -3100

c) 654 +{ 374 - [ 654 - ( +126)]}

= 654 + [ 374 -( 654 - 126)]

= 654 + ( 374 - 654 + 126)

= 654 + 374 - 654 + 126

= ( 654 - 654 ) + ( 374 + 126 )

= 0 + 500 = 500

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