a1=b1,a4=b4 所以,a4-a1=b4-b1 即 3d=b1(d^3-1)……⑴
a4=b4,a10=b10 所以,a4-a1=b4-b1 即 6d=b1(d^3)(d^6-1)=b1(d^3)(d^3-1)(d^3+1)……⑵
由题意知 d≠0 a1=b1≠0
2*⑴=⑵ 得 2*(d^3-1)=(d^3)(d^3-1)(d^3+1) d^-1≠0
所以 (d^3)^2+(d^3)-2=0 解之得 d^3=-2 d=-三次根号2
回代求a1=-d=三次根号2
b16=b1*d^15=-32b1=a1+33d=a34
答略.(若是计算没问题就没有问题了)