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a) 3a + 4b - 5c - 2a - 3b + 5c
= ( 3a - 2a ) + ( 4b - 3b ) - ( 5c - 5c )
= a + b
b) 7a + 3b - 4c - 3a + 2b - 2c - 4a + b - 2c
= ( 7a - 3a - 4a ) + ( 3b + 2b + b ) - ( 4c + 2c + 2c )
= 6b - 8c
a) 3a + 4b - 5c - 2a - 3b + 5c
= (3a - 2a) + (4b - 3b) - (5c - 5c)
= a + b - 0 = a + b
b) 7a + 3b - 4c - 3a + 2b - 2c - 4a + b - 2c
= (7a - 3a - 4a) + (3b + 2b + b) - ( 4c + 2c + 2c)
= 0 + 6b - 8c = 6b - 8c
1 , a - ( a - b - c ) - ( b - c -a ) - ( c - b -a )
= a - a + b + c - b + c + a - c + b + a
= (a-a+a) + (b-b+b) + (c-c+c)
= a+b+c
2 , - ( a + b + c ) - ( b - c -a ) + ( 1 - a - b ) - ( c - 3b )
= -a - b - c - b + c + a + 1 - a - b - c + 3b
= (a+a-a) - (b+b+b) + (c-c+c) + 3b
= a - 3b + c + 3b
= a+c + (3b - 3b)
= a+c + 0
= a+c
3 , ( b - c - 6 ) - ( 7 - a + b ) + c
= b - c - 6 - 7 + a - b + c
= (b-b) + (c-c) - (6+7) + a
= 0 + 0 - 13 + a
= -13 + a
4 , - ( 3b - 2a - c ) - ( a - b - c ) - ( a - 2b -+ 2c )
= -3b + 2a + c - a + b + c - a + 2b - 2c
= -3b + (2b + b) + (c + c) - (a+a) +2a - 2c
= -3b + 3b + 2c - 2a + 2a - 2c
= (3b - 3b) + (2c - 2c) + (2a + 2a)
= 0 + 0 + 0
= 0
chỉ bt lm đến đây thoy
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1) a - ( a - b - c ) - ( b - c - a ) - ( c - b - a )
= a - a + b + c - b + c + a - c + b + a
= 2a + b + c
2) - ( a + b + c ) - ( b - c - a ) + ( 1 - a - b ) - ( c - 3b )
= -a - b - c - b + c + a + 1 - a - b - c + 3b
= 1 - a - c
1,a-(a-b-c)-(b-c-a)-(c-b-a)
=a-a+b+c-b+c+a-c+b+a
=2a+b+c
2,-(a+b+c)-(b-c-a)+(1-a-b)-(c-3b)
=-a-b-c-b+c+a+1-a-b-c+3b
=1-a-c
3,(b-c-6)-(7-a+b)+c
=b-c-6-7+a-b+c
=a-13
4,-(3b-2a-c)-(a-b-c)-(a-2b+2c)
=-3b+2a+c-a+b+c-a+2b-2c
=0
5,(4a-3b+2c)-(4b-3c-2a)-(4c-3a+2b)+(a-b)-c
=4a-3b+2c-4b+3c+2a-4c+3a-2b+a-b-c
=(4a+2a+3a+a)-(3b+4b+2b+b)+(2c+3c-4c-c)
=10a-10b+0
=10.(a-b)
6,
2a-{a-b[a-b-(a+b+c)+2b]-c-b}
=2a-{a-b[a-b-a-b-c+2b]-c-b}
=2a-a-bc+c+b
=a-bc+c+b
=(a+b)-b(c-1)
a - ( a - b - c ) - ( b - c - a ) - ( c - b - a)
= a - a + b + c - b + c + a - c + b + a
= ( a -a + a ) + ( b - b + b ) + ( c + c - c) ( vì mình ko có ngoặc vuông nên chỉ thế này thôi)
= a + b + c
Bạn tự làm hết nha
1)=>a-a+b+b-b+c+a-c+b+a=2a+2b+c=2(a+b)+c
2)=>-a-b-c-b+c+a+1-a-b-c+3b=-a
3)=>b-c-6-7+a-b+c=-13+a
4)-3b+2a+c-a+b+c-a+2b-2c=0
5)=>4a-3b+2c-4b+3c+2a-4c+3a-2b+a-b-c=-2a-10b-2c