a(b+c)-a(b+d)=a(c-d) a(b-c)+a(d+c)=a(b+d) a.(b-c)-a.(b+d)=-a.(c+d) (a+b).(c+d)-(a+d).(b+c)=(a-c).(d-b) Giải giúp mik với ạ Thanks ạ

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1. a, Ta có: a(b+c)-a(b+d)=ab+ac-ab-ad=ac-ad=a(c-d) (đpcm)

   b,Ta có: a(b-c)+a(d+c)=ab-ac+ad+ac=ab+ad=a(b+d) (đpcm)

   c,Ta có: a(b-c)-a(b+d)=ab-ac-ab-ad=-ac-ad=-a(c+d) (đpcm)

   d,Ta có: (a+b)(c+d)-(a+d)(b+c)=ac+ad+bc+bd-ab-ac-bd-dc=ad+bc-ab-dc=a(d-b)-c(d-b)=(d-b)(a-c) (đpcm)

   Chúc bạn học tốt nhé! ^^

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

   =a(b+c-b-d)

   =a(c-d) =VP

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

   =a(b-c+d+c)

   =a(b+d+) =VP

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

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

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

   =-a(c+d) =VP

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

   =ac+ad+bc+bd-ab-ac-bd-dc

   =ad-ab+bc-dc

   =(ad-ab)+(bc-dc)

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

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

   =(a-c)(d-b) =VP.

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