网址:http://m.1010jiajiao.com/timu_id_2931341[举报]
等差数列中,,则该数列的前5项和为( )
A .32 B. 20 C.16 D.10
等差数列中,,则该数列的前5项和为 ( )
A.32 B. 20 C.16 D.10