等差数列an的前n项和为sn,若s7>s8>s6,则下列结论:(1)a7=0 (2)a8>0 (3)s13>0 (4)s14

问题描述:

等差数列an的前n项和为sn,若s7>s8>s6,则下列结论:(1)a7=0 (2)a8>0 (3)s13>0 (4)s14