Question

Bỏ dấu ngoặc rồi rút gọn biểu thức

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

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

Answer 1

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

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

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

=0+2b-a-c

=2b-a-c

Answer 2

a)

\(\left(a+b\right)-\left(a-b\right)-\left(a+c\right)\)

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

\(=\left(a+a-a+a\right)+\left(b+b\right)-\left(c+c\right)\)

\(=2b-2c\)

b)

\(\left(a+b-c\right)+\left(a-b+c\right)-\left(b+c-a\right)-\left(a-b-c\right)\)

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

\(=\left(a+a-a+a\right)+\left(b-b-b+b\right)+\left(c-c-c+c\right)\)

\(=2a\)

Answer 3

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

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

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

= (-a) + 2b - c

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

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

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

= 2a

Answer 4

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

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

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

=0+0+0+0+0+2a

=2a