高考数列复习等差数列与等比数列对比小结:等差数列等比数列一、定义1(2)nnaadn1(2)nnaqna二、公式1.11naand,nmaanmdnm2.12nnnaaS112nnnad1.11nnaaq,()nmnmaaqnm2.11111111nnnnaqSaqaaqqqq三、性质1.,,2abcbac成等差,称b为a与c的等差中项2.若mnpq(m、n、p、*q),则mnpqaaaa3.nS,2nnSS,32nnSS成等差数列1.2,,abcbac成等比,称b为a与c的等比中项2.若mnpq(m、n、p、*q),则mnpqaaaa3.nS,2nnSS,32nnSS成等比数列