Toán Cho a,b thuộc Z a lớn hơn b.Tính a bt A= -(2a-b-c)-(-b-c-2a)-(a+b) 08/07/2021 By Amaya Cho a,b thuộc Z a lớn hơn b.Tính a bt A= -(2a-b-c)-(-b-c-2a)-(a+b)
A= -(2a-b-c)-(-b-c-2a)-(a+b) A=-2a+b+c+b+c+2a-a-b A=(-2a+2a)+(b+b-b)+c+c A=0+b+2c A=b+2c Vậy A=b+2c Trả lời
$A= -( 2a-b-c)-( -b-c-2a)-( a+b)$
= $-2a+b+c+b+c+2a-a-b$
= $b+b-b+c+c-a$
= $b-a+2c$
A= -(2a-b-c)-(-b-c-2a)-(a+b)
A=-2a+b+c+b+c+2a-a-b
A=(-2a+2a)+(b+b-b)+c+c
A=0+b+2c
A=b+2c
Vậy A=b+2c