Question

[My best friends (BFF)]

Thu gọn các biểu thức

a) (a + b + c) - (a - b + c)

b)(a + b - c) + (a - b) - (a - b - c)

c) - (a - b - c) + ( -a + b - c) - ( -a - b + c)

Answer 1

[Kiêm Hùng]

\(a.\left(a+b+c\right)-\left(a-b+c\right)=a+b+c-a+b-c=2b\\ b.\left(a+b-c\right)+\left(a-b\right)-\left(a-b-c\right)=a+b+c+a-b-a+b+c=a+b+2c\\ c.-\left(a-b-c\right)+\left(-a+b-c\right)-\left(-a-b+c\right)=-a+b+c-a+b-c+a+b-c=-a+3b-c\)