【解析】
(1) ∵ ········································ 2分
由得········································ 4分
整理得
∴ ····························································································· 6分
∵ ∴ ·································································· 7分
(2) ∵
∴····························································· 8分
即····················································································· 9分
∴
∴ ················································································· 10分
∴ ································· 13分
【解析】略