ab减去a2-ab+b2等于(  ) A.a2+2ab+b2 B.-a2-2ab+b2 C.-a2+2ab-b2 D.-a2+2ab+b2

问题描述:

ab减去a2-ab+b2等于(  )
A. a2+2ab+b2
B. -a2-2ab+b2
C. -a2+2ab-b2
D. -a2+2ab+b2

ab-(a2-ab+b2)=ab-a2+ab-b2=-a2+2ab-b2
故选C.