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E=(-a-b+c+d)-(d+c-b-2a)
E=-a-b+c+d-d-c+b+2a
E=-a+(-)b+c+d+(-d)+(-c)+b+2a
E=-a+(-b)+c+d+(-d)+(-c)+b+2a
E=(2a-a)+(-b+b)+(-d+d)+(-c+c)=a+0+0+0=a
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) - (b+b+b) + (c-c) + (-a) + (-c) + 3b
= 0 - 3b + 0 + (-a) + (-c) + 3b
= (3b-3b) + (-a) + (-c)
= 0 + (-a) + (-c)
= (-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
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 - b [ ( a - a ) - (b+b) - c + 2b ] - c - b }
= 2a - { a - b [ 0 - 0 - 2b - c + 2b ] - c - b }
= 2a - { a- b [ (2b - 2b) - c ] - c - b }
= 2a - { a - b [ 0 - c ] - c - b }
= 2a - { a - b.(-c) - c - b}
= 2a - a - b.(-c) - c - b
= 1a - (-b).c - c - b
= a - (-b).c - c.1 - b
= a - [(-b) - 1].c - b
ko chắc lắm
A =(a+b-2c) -(-a+b+c) -(2a-b-c)
= a+b-2c+a-b-c-2a+b+c
= b-2c
B=-(2a-b+c) + (b-2c-3a) -(-5a-3c+b)
= -2a+b-c+b-2c-3a+5a+3c-b
= b-c
C=(3a-b-2c)-( 2b+3c-a) +(2a-3b)
= a-b-2c-2b-3c+a+2a-3b
= -6b-5c
D=(5a-3b+c) +( 2a-3b+5) -( b-c+a)
= 5a-3b+c+2a-3b+5-b+c-a
= 6a-7b+2c
\(A=\left(a+b-2c\right)-\left(-a+b+c\right)-\left(2a-b-c\right)\)
\(=a+b-2c+a-b-c-2a+b+c=b-2c\)
\(B=-\left(2a-b+c\right)+\left(b-2c-3a\right)-\left(-5a-3c+b\right)\)
\(=-2a+b-c+b-2c-3a+5a+3c-b=b\)
\(C=\left(3a-b-2c\right)-\left(2b+3c-a\right)+\left(2a-3b\right)\)
\(=3a-b-2c-2b-3c+a+2a-3b=6a-6b-5c\)
\(D=\left(5a-3b+c\right)+\left(2a-3b+5\right)-\left(b-c+a\right)\)
\(=5a-3b+c+2a-3b+5-b+c-a=6a-7b+2c\)
a) A = (a - 2b + c) - (a - 2b - c)
= a - 2b + c - a + 2b + c
= (a - a) - (2b - 2b) + (c + c)
= 2c
b) tương tự trên
c) C = 2(3a + b - 1) - 3(2a + b - 2)
= 6a + 2b - 2 - 6a - 3b + 3
= (6a - 6a) + (2b - 3b) - (2 - 3)
= 0 - b + 1
= -b + 1
d) D = 4(x - 1) - (3x + 2)
= 4x - 4 - 3x - 2
= (4x - 3x) - (4 + 2)
= x - 6
a)
\(A=\left(-a-b+c\right)-\left(-a-b-c\right)\)
\(A=-a-b+c-\left(-a\right)+b+c\)
\(A=-a+\left(-b\right)+c+a+b+c\)
\(A=\left[\left(-a\right)+a\right]+\left[\left(-b\right)+b\right]+\left(c+c\right)\)
\(A=0+0+2c\)
\(A=2c\)
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b)
Cách 1 : \(A=\left(-1-\left(-1\right)+\left(-2\right)\right)-\left(1-\left(-1\right)-\left(-2\right)\right)\)
\(A=-1-\left(-1\right)+\left(-2\right)-\left(-1\right)+\left(-1\right)+\left(-2\right)\)
\(A=-1+1+\left(-2\right)+1+\left(-1\right)+\left(-2\right)\)
\(A=\left[\left(-1\right)+1+1+\left(-1\right)\right]+\left[\left(-2\right)+\left(-2\right)\right]\)
\(A=0+\left(-4\right)=\left(-4\right)\)
Cách 2 : Từ ý a suy ra :
\(A=\left(-2\right)\cdot2=\left(-4\right)\)
a) Ta có: -a - b - b = -a - b + c
Vậy: (-a-b+c) - (-a-b-c) = (-a-b+c) - (-a-b+c) = (-a-b+c) : 2
b) (-1-1+-2) : 2 = (-2+-2) : 2 = (-4) : 2 = -2
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
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(2a-3b)-(5b-d)+(8b-d)
\(=2a-3b-5b+d+8b-d\)
\(=2a+\left(8b-3b-5b\right)+\left(d-d\right)\)
=2a
\(\left(a+b\right)-\left(d-4b\right)-\left(c-10d\right)\)
\(=a+b-d+4b-c+10d\)
\(=a+5b+11d-c\)
a) (3a-2b+c)-(2a+b)-(c-a)
= 3a - 2b + c - 2a - b - c + a
= 3a - 2b - b + c - c - 2a + a
= 3a - (2b + b) + (c - c) - (2a - a)
= 3a - 3b + 0 - a
= 3a - a - 3b
= 2a - 3b
b) (a-b)-(b+c)-(c+a)
= a - b - b - c - c - a
= a - a - b - b - c - c
= ( a - a) - ( b + b) - ( c + c)
= 0 - 2b - 2c
b) (a-b)-(b+c)-(c+a)
= a - b - b - c -c - a
= (a - a ) - ( b + b ) - ( c + c )
= 0 - 2b - 2c
= -2b - 2c
= -(2b + 2c)
= -2(b+c)