a-b+a+b+c-a+b+c
-a+b+c-a+b-c-(-a)-b+c
a, ( a - b ) + ( a + b + c ) - ( a - b - c )
= a - b + a + b + c - a - b - c
= ( a - b + a + b ) + c - a - b - c
= 0 + c - a - b - c
= c - a - b - c
b, ( -a + b + c ) - ( a - b + c ) - ( -a + b - c )
= (-a) + b + c - a - b + c - ( - a ) + b - c
Tự làm tiếp nha
a, ( a - b ) + ( a + b + c ) - ( a - b - c )
= a - b + a + b + c - a - b - c
= ( a - b + a + b ) + c - a - b - c
= 0 + c - a - b - c
= c - a - b - c
b, ( -a + b + c ) - ( a - b + c ) - ( -a + b - c )
= (-a) + b + c - a - b + c - ( - a ) + b - c
Phần sau dễ rồi bạn tự giải đi
a, (a-b)+(a+b+ c)-(a-b-c)
=a-b+a+b+c-a+b+c
=(a-a)+(b-b)+(c-c)
= 0 + 0 +0
=0