(a+b-c)+(a+b)-(a-b-c)=a+b-c+a+b-a+b+c=2b

(a+b-c)+(a+b)-(a-b-c)=a+b-c+a+b-a+b+c=a+3b

a: =b-c-a+c+1-a-b+c

=-2a+1

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

=c-3b+a

c: =2(a-b-b+c-c+a)

=2(2a-2b)

=4a-4b

a) \(\left(b-c\right)-\left(a-c-1\right)-\left(a+b-c\right)\)

\(=b-c-a+c+1-a-b+c\)

\(=c-2a+1\)

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

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

\(=a-3b+c\)

c) \(2\cdot\left(a-b\right)-2\cdot\left(b-c\right)-2\cdot\left(c-a\right)\)

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

\(=2\cdot\left(2a-2b\right)\)

\(=4a-4b\)

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

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

=-a+b-2c

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

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

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

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

\(=2a-b+3c\)

k mk nha 

thank you very much

(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 + 0 - 0

= 2a

(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 + 0 + 0

= 2a

là A=(-a-b+c).(-a-b-c)hả

ko pt mà mấy bạn cứ xông zô trả lời,phí giấy của olm quá

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

=ab+ac-ba+bc

=ac+bc

=c.(a+b)

a,  a-[(-b-c)-(a-c)]=a-[-b-c-a+c]=a+b+c+a-c=2a+b-c

b,  b-(a-c)-(a-b+c)=b-a+c-a+b-c=2b-2a=2(b-a)

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