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?(求详解)

来源:学生作业帮助网 编辑:六六作业网 时间:2024/07/17 15:55:33
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?(求详解)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?(求详解)若{an}是等比数列,其公比

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?(求详解)
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?(求详解)

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?(求详解)
等比数列,其公比是q
∴a5=q*a4,a6=q*a5=q^2*a4
-a5,a4,a6成等差数列
∴a4-(-a5)=a6-a4
a4+q*a4=q^2*a4=a4
2+q-q^2=0
(q+1)(q-2)=0
∴ q=-1
或者q=2