$$√{9 + 2√{14}} = √{(√7)^2 + 2 * √7 * √2 + (√2)^2} = √{(√7 + √2)^2} = √7 + √2$$
$$√7 - √2 - \frac{5}{√7 + √2}$$
$$\frac{5}{√7 + √2} = \frac{5(√7 - √2)}{(√7 + √2)(√7 - √2)} = \frac{5(√7 - √2)}{7 - 2} = \frac{5(√7 - √2)}{5} = √7 - √2$$
$$√7 - √2 - (√7 - √2) = √7 - √2 - √7 + √2 = 0$$
Ответ: 0