ok i need help on find aymptotes

2.) find the slant asymptote of the curve. This, use it to help graph the curve.

so i have a equation like this

Y= x^2 + 9 / x

y= x^2 - 2x - 1/x

y= x^3/x2-1

can u help and teach me what to do , cause my teacher told us to use long division to find the slant asympototes.