A = ( a + b) - ( a -b) + ( a - c) - ( a + c)
A = a + b -a + b + a - c - a - c
A = ( a -a + a - a ) + b + b - ( c -c )
A = 0 + b + b - 0
A = b + b
b)
B= ( a + b - c) + ( a - b + c) - ( b + c - a ) - (a - b - c )
B = a + b - c + a - b + c - b - c + a - a + b + c
B= (a + a - a ) + ( b - b - b + b) - ( c + c - c + c)
B= a + 0 - c + c
B = a - c + c
@skymeo gửi bn ạ . Chúc bn hc tốt!!