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a)= a-c+d-c+a-d
=2a-2c=2(a-c)
b)=-a-b+c-d+a-b-c-d
=-2b-2d
=2.(-b)-2d=2(-b-d)
c)=ab-ac-ad-ab-ac+ad
=-2.ac
a) ( a- b) + ( c+ d) = a - b + c - d = ( a+ c ) - ( b+ d)
b) ( a- b ) - ( c- d)= a- b - c + d = ( a+ d) - ( b + c)
1)-(a+b-c)+(a-b-c)=a-b+c+a-b-c=-2b
2)a(b+c)-a(b+d)=a(b+c-b-d)=a(c-d)
3)a(b-c)+a(d+c)=a(b-c+d+c)=a(b+d)
chúc hok tốt :))))))
ak ở câu 1 sửa lại chút
1)-(a+b-c)+(a-b-c)=-a-b+c+a-b-c=-2b
1.a)(a + b - c) - (b - c + d)
= a + b - c - b + c - d
= ( b - b ) + ( - c + c ) + a - d
= 0 + 0 + a - d
= a - d
b) -(a -b + c) + (a - b + d)
= - a + b - c + a - b + d
= ( - a + a ) + ( b - b ) + d - c
= 0 + 0 + d - c
= d - c
c) (a + b) - (-a + b - c)
= a + b + a - b + c
= ( a + a ) + ( b - b ) + c
= 2a + 0 + c
= 2a + c
d) -(a + b) + (a + b + c)
= -a - b + a + b + c
= c
a) a.(b+c)-d.(b+c)
=>(b+c).(a-d) (giút gọn thừa số chung)
thay a-d=-7
b+c=12
=>-7.12=-84
a) a.(b+c)-d.(b+c)
= (a-d).(b+c)
Thay a-d=-7, b+c=12
Ta co (a-d).(b+c)=-7.12=-84
b) ax-ay+bx-by
= a(x-y)+b(x-y)
= (a+b).(x-y)
That a+b=25, x-y=-8
Ta co (a+b).(x-y)=25.(-8)=-200
aa) -(345+96345+96)+(−155+1996−155+1996)
=−345−96−155+1996=−345−96−155+1996
== (−345−155−345−155) - (96−199696−1996)
=−500+1900=−500+1900
=1400=1400
bb) (−456+95−456+95)-(-456+95456+95)-192192
=−456+95+456−95−192=−456+95+456−95−192
== (−456+456−456+456) + (95−9595−95) -192192
=−192=−192
cc) (a−b+ca−b+c)- (c−bc−b)+aa
=a−b+c−c+b+a=a−b+c−c+b+a
== (a+aa+a) + (−b+b−b+b) + (c−cc−c)
=2a=2a
dd)-(a−b+ca−b+c)+(c−bc−b)+aa
=−a+b−c+c−b+a=−a+b−c+c−b+a
== (−a+a−a+a) + (b−bb−b) + (−c+c−c+c)
=0=0
ee) (a−b+ca−b+c)+(c−bc−b)+aa
=a−b+c+c−b+a=a−b+c+c−b+a
== (a+aa+a) + (−b−b−b−b) + (c+cc+c)
=2a−2b+2c
a) ( a + b + c ) - ( b - c + d )
= a + b + c - b + c - d
= a + 2c - d
b) -(-a - b + c ) + ( a - b + d )
= a + b - c + a - b + d
= 2a - c + d
c) ( a + b ) - ( -a + b - c )
= a + b + a - b + c
= 2a + c
d) -(a + b) + ( a + b + c )
= -a - b + a + b + c
= c
Học tốt~