等差数列{an}中,a1+a3+a5=-12,且a1·a3·a5=80,求通项an

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等差数列{an}中,a1+a3+a5=-12,且a1·a3·a5=80,求通项an

等差数列{an}中,a1+a3+a5=-12,且a1·a3·a5=80,求通项an
等差数列{an}中,a1+a3+a5=-12,且a1·a3·a5=80,求通项an

等差数列{an}中,a1+a3+a5=-12,且a1·a3·a5=80,求通项an
a1=a3-2d
a5=a3+2d
a1+a3+a5=a3-2d+a3+a3+2d=3a3=-12
a3=-4
a1×a3×a5=(-4-2d)×(-4)×(-4+2d)=80
16-4d^2=-20
d=-3
an=5-3n

an=3n-13或an=-3n+5