23)Simplify \(\frac{x^3}{x-y} + \frac{y^3}{y-x}\)
Answer: \(\frac{x^3}{x-y} + \frac{y^3}{y-x} = \frac{x^3}{x-y} - \frac{y^3}{x-y}\)
\(= \frac{x^3 - y^3}{x-y}\)
\(= \frac{(x-y)(x^2+xy+y^2)}{x-y}\)
\(= x^2 + xy + y^2\)