4. Упростить выражение: 3 x-3 + x+15 x²-9 - 2 x

$$\frac{3}{x-3} + \frac{x+15}{x^2-9} - \frac{2}{x} = \frac{3}{x-3} + \frac{x+15}{(x-3)(x+3)} - \frac{2}{x} = $$ $$\frac{3x(x+3) + x(x+15) - 2(x-3)(x+3)}{x(x-3)(x+3)} = $$ $$\frac{3x^2+9x + x^2+15x - 2(x^2-9)}{x(x-3)(x+3)} = $$ $$\frac{3x^2+9x + x^2+15x - 2x^2+18}{x(x-3)(x+3)} = \frac{2x^2+24x+18}{x(x-3)(x+3)} = \frac{2(x^2+12x+9)}{x(x-3)(x+3)}$$

Ответ: $$\frac{2(x^2+12x+9)}{x(x-3)(x+3)}$$