若{an}是等比数列,其公比是q,且-a5,a4,a6成等差数列,则q等于A,1或2B,1或-2C,-1或-2D,-1或2

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若{an}是等比数列,其公比是q,且-a5,a4,a6成等差数列,则q等于A,1或2B,1或-2C,-1或-2D,-1或2若{an}是等比数列,其公比是q,且-a5,a4,a6成等差数列,则q等于A,

若{an}是等比数列,其公比是q,且-a5,a4,a6成等差数列,则q等于A,1或2B,1或-2C,-1或-2D,-1或2
若{an}是等比数列,其公比是q,且-a5,a4,a6成等差数列,则q等于
A,1或2
B,1或-2
C,-1或-2
D,-1或2

若{an}是等比数列,其公比是q,且-a5,a4,a6成等差数列,则q等于A,1或2B,1或-2C,-1或-2D,-1或2
a4=a1*q^3
-a5=a1*q^4
a6=a1*q^5
2a4=a6-a5
2*a1*q^3=a1*q^3(q^2-q)
得：q^2-q-2=0
q=2或q=-1
选D

我错了楼上对的

根据题意有：
2a4=a6-a5
2a1*q^3=a1*q^5-a1*q^4
2q^3=q^5-q^4
2=q^2-q
q^2-q-2=0
(q-2)(q+1)=0
所以q=2，或者-1，所以选择D.

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