已知数列{an}是等差数列,{bn}是等比数列,且a1=b1=2,b4=54,a1+a2+a3=b2+b3,求数

4 = b1* q^3,所以公比q = 3,b2 = b1*3 = 6,b3 = b1*3*3 = 18。a1+a2+a3 = 3*a2 = 6+18,所以a2 = 8,所以公差d = a2 -a1 = 6。a3 = 8+6 = 14。