Question

下列各式计算正确的是(    )

A.2(a+b)+c=2a+b+c                      B.3(a+b)+3(b-a)=0

C. +=2                    D.a+b+3a-5b=4a-4b

Answer 1

解析:A.2(a+b)+c=2a+2b+c≠2a+b+c;

B.3(a+b)+3(b-a)=6b≠0;

C. +=0≠2.

答案:D