解:〔2x^(n+5)-3x^(n+4)-4x^(n+3)〕/5x^(n+3) =〔颤胡2x^2*x^(n+3)-3x*x^(n+3)-4x^(n+3)〕/5x^(n+3) =(2x^2-3x-4)/5 把 x=2代入念首(x+1)(x-4)/5得: (2x^2-3x-4)/5 =(2*2^2-3*2-4)/5 =-2/仔洞数5