Question

Rút gọn biểu thức sau :

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

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

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

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

Answer 1

a) = -a + c - a + b - c

= -2a + b

b) = -a + b - c - a - b - c

= -2a -2c

c) = a+b-a+b+a-c-a-c

= 2b - 2c

d) a + b - c + a - b +  c - b - c + a - a + b + c

= 2a 

Answer 2

a)-(a-c)-(a-b+c)                   Dễ như bèo à

=-a+c-a+b-c

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

=0+0+b

=b