答:
等比数列的公比q
A3=A1*q^2
A5=A1*q^4
A7=A1*q^6
代入:A3*A5*A7=8得:
A1*A1*A1*q^12=8
(A1*q^4)^3=2^3
A1*q^4=2
所以:A2*A8=A1*A1*q^8=(A1*q^4)^2=2^2=4
所以:A2*A8=4
答:
等比数列的公比q
A3=A1*q^2
A5=A1*q^4
A7=A1*q^6
代入:A3*A5*A7=8得:
A1*A1*A1*q^12=8
(A1*q^4)^3=2^3
A1*q^4=2
所以:A2*A8=A1*A1*q^8=(A1*q^4)^2=2^2=4
所以:A2*A8=4