已知-1,a1,a2,-4成等差数列,-1,b1,b2,b3,-4成等比数列,求(a2-a1)/b2
人气:130 ℃ 时间:2020-05-31 13:27:56
解答
由-4=-1+3d,∴公差d=-1,
a1=-2,a2=-3.
由-4=(-1)×q^4=-4
∴公比q²=2(q²=-2舍去)
q=±√2,有两解.
有-1,-√2,-2,-2√2,-4
或-1,√2,-2,2√2,-4.
(a2-a1)/b2=(-1)/(-2)=1/2.
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