等比数列题!a3(下标)=3/2 S3(下标)=9/2 求a1(下标)和q
问题描述:
等比数列题!a3(下标)=3/2 S3(下标)=9/2 求a1(下标)和q
答
a1+a1*q+a1*q^2=9/2
a1*q^2=3/2
解得a1=3/2 q=1或者a1=6 q=-1/2