b) Biểu thức ( - a - b + c ) - ( - a - b - c )
= [ - 1 - ( -1 ) + ( - 2 ) ] - [ - 1 - ( - 1 ) - ( - 2 ) ]
= - 1 + 1 - 2 + 1 - 1 - 2
= ( - 1 + 1 ) + ( 1 - 1 ) + ( - 2 - 2 )
= 0 + 0 + ( - 4 )
= - 4
Tick nha
a) Rút gọn A
A = ( - a - b + c ) - ( - a - b - c )
A = - a - b + c + a + b + c
A = ( - a + a ) + ( - b + b ) + ( c + c )
A = 0 + 0 + ( c + c )
A = 0 + c . 2
A = c . 2