等差数列中a3a7=-16 a4+a6=0求an前n项和应是a4+a5=0

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等差数列中a3a7=-16 a4+a6=0求an前n项和应是a4+a5=0
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等差数列中a3a7=-16 a4+a6=0求an前n项和应是a4+a5=0
等差数列中a3a7=-16 a4+a6=0求an前n项和
应是a4+a5=0

等差数列中a3a7=-16 a4+a6=0求an前n项和应是a4+a5=0
a4+a5=0
a5=-a4
d=a5-a4=-2a4
a3a7
=(a4-d)(a4+3d)=-16
3a4*(-5a4)=-16
a4=16/15
an=96/5-(32/15)n