高中简单的数列问题1.等比数列{an}中,a2=1/6,a6=1/96,a1=?2.等比数列{an}中a1+a3=10,

a6/a2=q^4
=>
(1/96)/(1/6)=q^4
=>
1/16=q^4
=>
q=0.5或q=-0.5
a4+a6
=a1*q^3+a3*q^3
=(a1+a3)*q^3
=>
5/4=10*q^3
=>
1/8=q^3
=>
q=0.5
=>
a1+a1*q^2=10
=>
a1(1+1/4)=10
=>
a1=8
=>
an=8*(0.5)^(n-1)
等比中项
=>
b/a=c/b
=>
b^2=ac
=>
abc=b^3
=>
b^3=64
=>
b=4