令y=n^2-17n+73=a^2则n^2-17n+72=a^2-1∴(n-8)(n-9)=(a+1)(a-1)③（十字相乘）原方程(视a为常数)Δ=4a^2-3要使该方程有整数解,有Δ=4a^2-3=b^2易得a=-1或1(用Δ知识去证明)代入③,③=0这就表明③成立的条件为a=-1或1...