https:/img.cdnjtzy.com/zyb_b56d5b5fa6f1ae187047a6d8e2973723.jpg+(a)_(1) 1 1-|||-1 https:/img.cdnjtzy.com/zyb_b56d5b5fa6f1ae187047a6d8e2973723.jpg+(a)_(2) 1-|||-(7) _(n)= 其中 _(1)(a)_(2)... (a)_(n)neq 0.-|||-1 1 https:/img.cdnjtzy.com/zyb_b56d5b5fa6f1ae187047a6d8e2973723.jpg+(a)_(n)