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阅读下列解题过程: 1 5 + 4 = 1×( 5 - 4 ) ( 5 + 4 )×( 5 - 4 ) = ( 5 - 4 ) ( 5 ) 2 - ( 4 ) 2 = 5 - 4 = 5 -2; 1 6 + 5 = 1×( 6 - 5 ) ( 6 + 5 )×( 6 - 5 ) = 6 - 5 ( 6 ) 2 - ( 5 ) 2 = 6 - 5 . 请回答下列问题: (1)观察上面的解题过程,请直接写出式子 1 n + n+1 =______; (2)利用上面所提供的解法,请化简 1 2 +1 + 1 3 + 2 + 1 4 + 3 + 1 5 + 4 +…+ 1 10 + 9 的值.