因为an为等差数列,公差为d；bn为等比数列,公比为d所以a4＝a1+3d；b4＝b1×d^3；a1+3d＝b1×d^3（1）所以a10＝a1+9d；b10＝b1×d^9；a1+9d＝b1×d^9（2）将（1）/（2）得：（a1+3d）/（a1+3d）＝1/d^6,即：a1＝(9d-3d...