Cho A=a+b-5;B=-b-c+1;C=b-c-4;D=b-a Chứng minhA+B=C-D 17/07/2021 Bởi Serenity Cho A=a+b-5;B=-b-c+1;C=b-c-4;D=b-a Chứng minhA+B=C-D
A+B=a+b-5+(-b-c+1)
=a+b-5-b-c+1
=a-c-4
C-D=b-c-4-(b-a)
=b-c-4-b+a
=a-c-4
⇒A+B=C-D (=a-c-4)
A+B= a+b-5+ (-b)-c+1
= a-c-4
C-D= b-c-4-(b-a)
= b-c-4-b+a
= a-c-4
Vậy A+B=C-D