Giải:

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

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

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

\(\Leftrightarrow A=2b-2c\)

\(\Leftrightarrow A=2\left(b-c\right)\)

Vậy ...

a)

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 )

= 2b -2c

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

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

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

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

\(=c\)

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

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

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

\(=\left(2a-2a\right)+0+c\)

\(=c\)

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

A= a-b-a+b+c-2a-c+a

A= -a

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

B=a+b+c

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

a + (-b) - c  , tick nha

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

nhớ k cho mink nhé

B1:

a,  a+b+(-a)+b+a+(-c)+(-a)+(-c)=[a+(-a)+a+(-a)]+(b+b)+[(-c)+(-c)]=0+2.b+(-2).c

b,  a+b+(-c)+a+(-b)+c+(-b)+(-c)+a+(-a)+b+c=[a+a+a+(-a)]+[b+(-b)+(-b)+b]+[(-c)+c+(-c)+c]=2.a+0+0=2a

B2:

N=(a+b)-(a-b)+(a+b)=a+b+(-a)+b+a+b=[a+(-a)+a)+(b+b+b)=a+3.b

NẾU CẬU KHÔNG HIỂU THÌ CỨ HỎI NHÉ!

rút gọn biểu thức

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

b,B=-(a+b+c)-(a+b-5)

uk nha bạn

15+(1000-998)+(998-996)+(996-994)+....+(102-100)+(100-98)

= 15+1000-998+998-996+996-994+....+102-100+100-98

= 15 + 1000 - 98 = 917

\(15+\left(1000-998\right)+\left(998-996\right)+\left(996-994\right)+...+\left(102-100\right)+\left(100-98\right)=15+2+2+...+2=15+226\times2=467\)

15+(1000-998)+(998-996)+...+(102-100)+(100-98)

=15+1000-998+998-996+...+102-100+100-98

=15+1000+(998-998)+(996-996)+...+(102-102)+(100-100)-98

=15+1000+0+0+...+0+0-98

=917

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

$A=a+b-a-b+a-c-a-c$

$A=-2c$

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

a)(x+y).(x+y)=x(x+y)+y(x+y)=x^2+xy+xy+y^2=x^2+2xy+y^2

b)(x-y).(x-y)=x(x-y)-y(x-y)=x^2-xy-xy+y^2=x^2-2xy+y^2

c)(x+y).(x-y)=x(x-y)+y(x-y)=x^2-2xy+xy-y^2=x^2-y^2

nhớ liek nhé

a ,  = \(x^2+2xy+y^2\)

b, = \(x^2-2xy+y^2\)

c = \(x^2-y^2\)

Theo đầu bài ta có:
\(\left(a+b-c\right)+\left(a-b+c\right)-\left(b+c-a\right)-\left(a-b-c\right)\)
\(=a+b-c+a-b+c-b-c+a-a+b+c\)
\(=\left(a+a+a-a\right)+\left(b-b-b+b\right)+\left(c-c-c+c\right)\)
\(=2a\)

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

=2a nha bn

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

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

= 2a 

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ai chơi bang bang 2 kết bạn với mình

mình có nick có 54k vàng đang góp mua pika 

ai kết bạn mình cho

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

         \(=a.a+ab+ab+bb\)

         \(=a^2+2ab+b^2\)   

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

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

         \(=a^2-a.b-a.b+b^2\)

           \(=a^2-2ab+b^2\)

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

          \(=a.a+a.\left(-b\right)+ab+b.\left(-b\right)\)

          \(=a^2-a.b+a.b-b^2\)

           \(=a^2-b^2\)