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a) (a - b + c - d) - (a + b - + c + d) = a - b + c - d - a - b + c - d = -2b + 2c - 2d
b) (-a + b - c) + (a - b) - ( a - b + c) = -a + b - c + a - b - a + b - c = -a + b - 2c
c) -(a - b - c) + (b - c + d) - (a - b + c) = -a + b + c + b - c + d - a + b - c = -2a + 3b - c + d
`@` `\text {Ans}`
`\downarrow`
`a)`
`(a -b + c- d) - ( a+ b- +c+d)`
`= a - b + c - d - a - b + c - d`
`= (a-a) + (-b-b) + (c+c) + (-d-d)`
`= -2b + 2c - 2d`
`b)`
` ( -a + b - c) + ( a - b) - (a - b + c)`
`= -a + b - c + a - b - a + b - c`
`= (-a +a - a) + (b - b + b) + (-c-c)`
`= a + b - 2c`
`c)`
\( – ( a- b- c) + ( b – c+d) – ( a-b +c)\)
`= - a + b + c + b - c + d - a + b - c`
`= (-a -a) + (b + b + b) + (c-c-c) + d`
`= -2a + 3b - c + d`
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a,=a-b+c-d-a-b-c-d=-2b-2d\\ b,=-a+b-c+a-b-a+b-c=-a+b-2c\)
a) ( a - b + c -d ) - ( a+ b + c + d ) = a - b + c - d - a - b - c - d = -2b - 2d
b) ( -a + b -c ) + ( a - b ) - ( a- b + c ) = -a + b - c + a - b - a + b - c = -a + b - c - c = -a + b - 2c
c) - ( a - b - c ) + ( b - c + d ) - ( -a + b + d )
![](https://rs.olm.vn/images/avt/0.png?1311)
a) - ( - a + c – d ) – ( c – a + d )
= a - c - d - c + a + d
= (a + a) + (-c - c) + (-d + d)
= 2a - 2c
b) – ( a + b - c + d ) + ( a – b – c –d )
= - a - b + c - d + a - b - c - d
= (-a + a) + (-b - b) + (c - c) + (-d - d)
= -2b - 2d
a) - ( - a + c - d) - ( c - a + d )
= a - c + d - c + a - d
= 2a
b) - ( a+ b - c + d ) + ( a -b -c -d )
= - a-b+c-d+a-b-c-d
=-2d -2b
c) a(b-c-d) - a(b+c-d)
= a(b-c-d-b-c+d)
= ab-ac-ad-ab-ac+ad
= -2ab-2ac
d) (a+b)(c+d)-(a+d)(b+c)
= ac+ad+bc+bd - (ab+ac+bd+cd)
= ac+ad+bc+bd-ab-ac-bd-cd
=ad+bc-ab-cd
![](https://rs.olm.vn/images/avt/0.png?1311)
A, (a + b + c - d) - (a + b + c + d)
= a + b + c - d - a - b - c - d
= (a - a) + (b - b) + (c - c) - (d + d)
= 0 + 0 + 0 - 2d
= -2d
Ý b, c em xem lại xem sao chỗ chữ cái viết hoa chỗ lại viết thường là sao em nhỉ?
![](https://rs.olm.vn/images/avt/0.png?1311)
a, -( -a + c - d) - ( c - d + d) = a - c + d - c + d - d = a + d
b, - ( a+b-c+d) + (a-b-c-d) = -a -b+c-d + a-b-c-d = -2b + (-2c)= -2(b+c)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) -(-a + c - d) - (c - a + d) = a - c + d - c + a - d = (a + a) - (c + c) + (d - d) = 2a - 2c
b) -(a + b - c + d) + (a - b - c - d) = -a - b + c - d + a - b - c - d = (-a + a) - (b + b) + (c - c) - (d + d) = -2b - 2d
c) (a + b - c) - (b - c + d) = a + b - c - b + c - d = a + (b - b) - (c - c) - d = a - d
d) (b + a) + (c - d) - (c + a) - (b - d) = b + a + c - d - c - a - b + d = (b - b) + (a - a) + (c - c) - (d - d) = 0
e) (a - b) - (d + a) - (c - d) + (c + b) = a - b - d - a - c + d + c + b = (a - a) - (b - b) - (d - d) - (c - c) = 0
f) -a + (c - b) - (c + a - b) = - a + c - b - c - a + b = (-a - a) + (c - c) - (b - b) = -2a
a ) a - c + d - c + a - d = 2a - 2c
b ) -a - b + c - d + a - b - c - d = -2b - 2d
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![](https://rs.olm.vn/images/avt/0.png?1311)
\(a,\left(a-b+c-d\right)-\left(a+b+c+d\right)\)
\(=a-b+c-d-a-b-c-d\)
\(=-2b-2d\)
\(b,\left(-a+b-c\right)+\left(a-b\right)-\left(a-b+c\right)\)
\(=-a+b-c+a-b-a+b-c\)
\(=-a+b-2c\)
\(c,-\left(a-b-c\right)+\left(b-c+d\right)-\left(-a+b+d\right)\)
\(=-a+b+c+b-c+d+a-b-d\)
\(=b\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a)-(-a+c-d)-(c-a+d)=a-c+d-c+a-d=(a+a)-(c+c)+(d-d)=2a-2c=2(a-c)
b)-(a+b-c+d)+(a-b-c-d)=-a-b+c-d+a-b-c-d=(-a+a)-(b+b)+(c-c)-(d+d)=0-2b+0-2d=-2(b-d)
c)a(b-c-d)-a(b+c-d)=ab-ac-ad-ab-ac+ad=(ab-ac)-(ac+ac)-(ad-ad)=2ac
d)đề sai
e)(a+b)(c-d)-(a-b)(c+d)=ac+b-ad+b-(ac-b+ad-b)=ac+b-ad+b-ac+b-ad+b=(ac-ac)+(b+b+b+b)-(ad+ad)=4b-2ad=2(2b-ad)
f)(a+b)2-(a-b)2=a2+2ab+b2-(a2-2ab+b2)=a2+2ab+b2-a2+2ab-b2=(a2-a2)+(2ab+2ab)+(b2-b2)=4ab
mk k chắc đâu
a) = a - b + c - d - a - b - c - d
= -2b - 2d
b) = -a + b - c + a - b - a + b + c
= -a + b
c) = -a + b + c + b - c + d + a - b - d
= b
a,= -2b - 2d
b,=-a + b
c,=b