已知等比数列{an}满足a1+a2=3,a3+a4=6,则a7+a8=_.
问题描述:
已知等比数列{an}满足a1+a2=3,a3+a4=6,则a7+a8=______.
答
∵等比数列{an}满足a1+a2=3,a3+a4=6,
∴
,解得q2=2,
a1(1+q)=3
a1(1+q)•q2=6
∴a7+a8=a1(1+q)•q6=3•23=24.
故答案为:24.