若等比数列an满足a1=8,a2a3=-8,则a3+a4等于
问题描述：
若等比数列an满足a1=8,a2a3=-8,则a3+a4等于
答
a2a3
=a1q*a1q^2
=a1^2q^3=-8
q^3=-8/8^2=-1/8
q=-1/2
则 a3+a4=a1q^2+a1q^3=2-1=1