a) $$9\cdot \left(\frac{5}{6}\right)^2 = 9 \cdot \frac{25}{36} = \frac{25}{4} = 6.25$$
б) $$ \left(9\cdot \frac{5}{6}\right)^2 = \left(\frac{45}{6}\right)^2 = \left(\frac{15}{2}\right)^2 = \frac{225}{4} = 56.25$$
в) $$(-10)^6 = 1000000$$
г) $$-10^6 = -1000000$$
Ответ: a) 6.25; б) 56.25; в) 1000000; г) -1000000