3) а) \(\frac{x^2}{x^2-x}\); б) \(\frac{x^2-1}{x^2-x}\); в) \(\frac{x^2}{x^2+x}\); г) \(\frac{x^2-1}{x^2+x}\).

Разложим на множители: \(x^2-x=x(x-1)\), \(x^2+x=x(x+1)\), \(x^2-1=(x-1)(x+1)\).

1. \(\frac{x^2}{x^2-x}=\frac{x^2}{x(x-1)}=\frac{x}{x-1}\);
2. \(\frac{x^2-1}{x^2-x}=\frac{(x-1)(x+1)}{x(x-1)}=\frac{x+1}{x}\);
3. \(\frac{x^2}{x^2+x}=\frac{x^2}{x(x+1)}=\frac{x}{x+1}\);
4. \(\frac{x^2-1}{x^2+x}=\frac{(x-1)(x+1)}{x(x+1)}=\frac{x-1}{x}\).

Ответ: а) \(\frac{x}{x-1}\); б) \(\frac{x+1}{x}\); в) \(\frac{x}{x+1}\); г) \(\frac{x-1}{x}\).