Question

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

Answer 1

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

\(b,\left(a+b\right)-\left(b-a\right)+c=a+b-b+a+c=2a+c\)

\(c,-\left(a+b-c\right)+\left(a-b-c\right)=-a-b+c+a-b-c=-2b\)

\(d,a\left(b+c\right)-a\left(b+d\right)=ab+ac-ab-ad=ac-ad=a\left(c-d\right)\)

\(e,a\left(b-c\right)+a\left(d+c\right)=ab-ac+ad+ac=ab+ad=a\left(b+d\right)\)

Answer 2

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)

Answer 3

a ) 

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

 a - b + c - a -c = - b

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

0 + 0 - b = -b ( đpcm )

Answer 4

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

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

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

d) a.(b+c) -a.(b+d) =a.(b+c-b-d) = a.(c-d)   (đpcm)

e) a.(b-c) + a.(d+c) = a.(b-c+d+c) = a.(b+d)   (đpcm)