66. 1) $$rac{2x}{x-4} - \frac{5x-2}{16-x^2};$$

$$\frac{2x}{x-4} - \frac{5x-2}{16-x^2} = \frac{2x}{x-4} + \frac{5x-2}{x^2-16} = \frac{2x}{x-4} + \frac{5x-2}{(x-4)(x+4)} = \frac{2x(x+4)}{(x-4)(x+4)} + \frac{5x-2}{(x-4)(x+4)} = \frac{2x^2+8x+5x-2}{(x-4)(x+4)} = \frac{2x^2+13x-2}{(x-4)(x+4)} = \frac{2x^2+13x-2}{x^2-16}$$ Ответ: $$\frac{2x^2+13x-2}{x^2-16}$$