已知等差数列{an},若a1+a3+a5=9,则a2+a4=_.
问题描述:
已知等差数列{an},若a1+a3+a5=9,则a2+a4=______.
答
∵等差数列an中,a1+a5=2a3,
又由题意a1+a3+a5=9,∴3a3=9,a3=3,
则a2+a4=2a3=6,
故答案为:6.