Chứng tỏ :
a) ( a - b + c ) - ( a + c ) = -b
b) ( a + b ) - ( b - a ) + c = 2a + c
c) -( a + b - c ) + ( a - b - c ) = -2b
d) a.( b + c ) - a ( b + d ) = a.( c - d )
e) a.( b - c ) + a.(d + c ) = a.( b + d )
MK ĐANG CẦN GẤP , AI NHANH MK TICK , KT BN NHÉ
\(a,\left(a-b+c\right)-\left(a+c\right)=a-b+c-a-c=-b\)
\(b,\left(a+b\right)-\left(b-a\right)+c=a+b-b+a+c=2a+c\)
\(c,-\left(a+b-c\right)+\left(a-b-c\right)=-a-b+c+a-b-c=-2b\)
\(d,a\left(b+c\right)-a\left(b+d\right)=ab+ac-ab-ad=ac-ad=a\left(c-d\right)\)
\(e,a\left(b-c\right)+a\left(d+c\right)=ab-ac+ad+ac=ab+ad=a\left(b+d\right)\)
a) (a - b + c) - (a + c)
= a - b + c - a - c
= (a - a) - b + (c - c)
= -b
b) (a + b) - (b - a) + c
= a + b - b + a + c
= 2a + (b - b) + c
= 2a + c
c) - (a + b - c) + (a - b - c)
= -a - b + c + a - b - c
= (-a + a) - (b + b) + (c - c)
= -2b
d) a(b + c) - a(b + d)
= ab + ac - ab - ad
= (ab - ab) + (ac - ad)
= ac - ad
= a(c - d)
e) a(b - c) + a(d + c)
= a(b - c + d + c)
= a[b - (c - c) + d]
= d(b + d)