5x²-5=3x
所以5x²-2x-5=x
5x²-2x=x+5
5x²-5=3x
x²-1=3x/5
所以原式=x+5-1/x
=(x²+5x-1)/x
=(3x/5+5x)/x
=(3/5+5)/1
=28/5