a1=1,b1-a1=1,b1=2b2-a2=2,2q-r=2 (1)b3-a3=3,2q^2-r^2=3 (2)由（1）得 q=(2+r)/2代入（2）得1/2*(2+r)^2-r^2=3(2+r)^2-2r^2=64r+4-r^2=6r^2-4r+2=0(r-2)^2-2=0(r-2+√2）(r-2-√2）=0r1=2+√2,an=(2+√2)^(n-1)r2=2...