a. = a + b - a + b + a - c - a + c
= (a - a + a - a) + (b + b) + (-c + c)
= 0 + 2b + 0
= 2b
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)
= 2a + 0 + 0
= 2a
a) ( a + b ) - ( a - b ) + ( a - c ) - ( a - c )=a+b-a+b+a-c-a+c=(a-a+a-a)+(b+b)+(c-c)=2b
b) ( a + b -c ) + ( a - b + c ) - ( b + c - a ) - ( a- b - c )=a+b-c+a-b+c-b-c+a=(a+a+a)+(b-b-b)+(c-c-c)=3a-b-c
a) a+b-a+b+a-c-a+c=2b
b)a+b-c+a-b+c-b-c+a-a+b+c=2a
a,(a+b)-(a-b)+(a-c)-(a-c)
=a+b-a+b+a-c-a+c
=(a-b)+b+b+(a-a)+(-c+c)
=0+2b+0+0
=2b
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)
=2a+0+0+0+0+0
=2a
a) a+b - a+b + a-c - a+c
= 0
b)a+b-c + a-b+c - b-c+a - a+b+c
=????
đề của bạn nhầm ha sao ý,thế này đúng hơn nè
a,(a+b)-(a+b)+(a-c)-(a-c)
=a+b-a-b+a-c-a+c
=0
a) a+b-a+b+a-c-a+c=2b
b)a+b-c+a-b+c-b-c+a-a+b+c=2a
a) (a + b) - (a - b) + (a - c) - (a - c)
= a + b - a + b + a - c - a + c
= (a - a + a - a) + (b + b) + (-c + c)
= 0 + 2b + 0
= 2b
b) (a + b - c) + (a - b + c) - (b + c - s) - (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) (a + b) - (a - b) + (a - c) - (a - c)
= a + b - a + b + a - c - a + c
= (a - a + a - a) + (b + b) + (-c + c)
= 0 + 2b + 0
= 2b
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 + 0 + 0
= 2a
a)a+b-a+b+a-c-a+c
=a-a+c-c+a-a+b+b
=b+b
b)a+b-c+a-b+c-b-c+a-a+b+c
=(b-b+b-b)+(c-c+c-c)+(a+a+a-a)
=0+0+a+a+0
=a+a