關於yx2y5的百科

• .(3x-y)(x+2y)5的展開式中,x4y2的係數為(　　)A.110                  ...

• 問題詳情：.(3x-y)(x+2y)5的展開式中,x4y2的係數為()A.110                      B.120                C.130                D.150【回答】.A解析因為(x+2y)5展開式的通項為Tr+1=x5-r(2y)r,故分別令r=2,r=1,可得(...
• 2021-08-215279