是5x^2-3x-5=0
则5x^2-2x-5=x
5x^2-2x=x+5
5x^2-5=3x
所以x^2-1=3x/5
所以原式=x+5-1/x
=(x^2+5x-1)/x
=(3x/5+5x)/x
=3/5+5
=28/5