a2*a10+a4*a8=20,求a6^2
问题描述：
a2*a10+a4*a8=20,求a6^2
答
这题目出的,也没说是等差数列还是等比数列.应该是等比数列吧?
a2a10+a4a8
=a1^2q^10+a1^2q^10
=a6^2+a6^2
=2a6^2
=20
a6^2=10