设a1,d为实数,首项为a1,公差为d的等差数列an的前n项和为sn,满足s5s6+15=0,求d的取值范围

设a1，d为实数，首项为a1，公差为d的等差数列{an}的前n项和为Sn，满足S5S6+15=0，则d的取值范围是___ 设a1,d为实数,首项为a1,公差为d的等差数列{an}的前n项和为Sn,满足S5S6+15=0. 设a1,d为实数,首项a1,公差为d的等差数列an的前n项和为sn,满足s5s6+15=0,若s5=5求s6及a1,求d 设a1,d.为实数,首项为a1,公差为d的等差数列｛an｝的前n项和为SN,且满足S5S6 15=0及S5=5,求S6及 设a1,d为实数,首项为a1,公差为d的等差数列{an}的前n项和为Sn,满足S5S6 +15=0.1.若S5=5,求S 设a1 d 为实数 首项为a1 公差为d的等差数列an前n项和为Sn 满足 S5*S6+15=0 则d的取值范围是? a1d为实数,首项为a1,公差为d的等差数列an的前n项和为Sn,s5s6+15=0 设a1 d 为实数 首项为a1 公差为d的等差数列an前n项和为Sn 满足 S2*S6+15=0 , 设a1,d为实数,首项为a1,公差为d的等差数列{an}的前n项和为Sn,满足S5+S6+15=0. 设a1 d 为实数 首项为a1 公差为d的等差数列an前n项和为Sn 满足 S5*S6+15=0 ,若s5=5,求s6, 设公差为d的等差数列{an}的前n项和为Sn,若a1=1,-2/17 设等差数列{an}的首项a1及公差d都为整数,前n项和为sn.若a1>=6,a11>0,s14