x=16/(根号17＋1)=√17-1
所以
x+1=√17
x²+2x+1=17
x²+2x=16
x+2=16/x
x^3+2x^2-17x-3+16/x
=x^3+2x^2+x-18x-3+16/x
=x(x²+2x+1)-18x-3+16/x
=17x-18x-3+16/x
=-x-3+16/x
=-x-3+x+2
=-1