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`

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

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 )

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

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?

Cô oi chữ nó bị thế thoi, A và a giống nhau cô ah

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)

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 

 CÁC CÂU CÒN LẠI LÀM TƯƠNG TỰ NHÉ!!

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

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

\(=-2b-2d\)

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

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

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

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

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

\(=b\)

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