Question

rút gọn A=(-a+b-c)-(-a-b-c)

 

Answer 1

A=-a+b-c+a+b+c=(-a+a)+(b+b)+(c-c)=2b

Answer 2

A=(-a)+b-c+a+b+c

A=(-a)+a+b+b-c+c

A=0+2b+0

A=2b

Answer 3

A =a-b+c-a+b+c

=>A=(a-a)+(-b+b)+(c+c)

=>A=0+0+2c

=>A=2c