a) $$m = -2$$, $$n = -1$$:
$$\frac{(-2)^2 - (-1)}{3(-2)(-1)+2} = \frac{4 + 1}{6+2} = \frac{5}{8}$$
б) $$m = -3$$, $$n = 0$$:
$$\frac{(-3)^2 - 0}{3(-3)(0)+2} = \frac{9 - 0}{0+2} = \frac{9}{2}$$
в) $$m = 6$$, $$n = 4$$:
$$\frac{6^2 - 4}{3(6)(4)+2} = \frac{36 - 4}{72+2} = \frac{32}{74} = \frac{16}{37}$$
Ответ: а) $$\frac{5}{8}$$; б) $$\frac{9}{2}$$; в) $$\frac{16}{37}$$.