Question

[Diệu Anh Nguyễn]

cho:

A=a+b-5 B=-b-c+1 C=b-c-4 D=b-a

chung minh A+B=C+D

Answer 1

[Phương Trâm]

Ta có:

\(A+B=a+b-5+\left(-b\right)-c+1\)

\(=a-c+\left(-b+b\right)+\left(-5+1\right)\)

\(=a-c-4\)

\(C-D=\left(b-c-4\right)-\left(b-a\right)\)

\(=b-c-4-b+a\)

\(=b-b+a-c-4\)

\(=a-c-4\)

Vậy: \(A+B=C-D\)