题目

设P=1+5(x+1)+10(x+1)2+10(x+1)3+5(x+1)4+(x+1)5,则P等于(    )A.x5                 B.(x+2)5             C.(x-1)5                  D.(x+1)5 答案：解析:逆用二项式定理得B.答案:B