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Решите задачу:

$( \sqrt{15}+ \sqrt{5})*\sqrt{15}- \frac{5}{3} \sqrt{27}= \\ \sqrt{225}+ \sqrt{75}- \frac{15}{3} \sqrt{3}= \\ 15+\sqrt{75}-5 \sqrt{3}= \\ \\ 15+5\sqrt{3}-5 \sqrt{3}=15$

$( \frac{3}{9-x^{2}}+ \frac{1}{x-3}): \frac{x}{x^{2}-6x+9}\\ \\ ( \frac{3}{(x+3)(x-3)}+ \frac{1}{x-3}): \frac{x}{x^{2}-6x+9} \\ \\ ( \frac{3}{(x+3)(x-3)}+ \frac{1*(x+3)}{x-3}): \frac{x}{x^{2}-6x+9} \\ \\ 3+ (x+3): \frac{x}{x^{2}-6x+9} \\ \\ (6+ x) *\frac{x^{2}-6x+9}{x} \\ \\ \frac{(6+ x) *(x^{2}-6x+9)}{x} \\ \\ \frac{6x^{2}-36x+54+x^{3}-6x^{2}+9x}{x} \\ \\ \frac{x^{3}-27x}{x} \\ \\ \frac{x(x^{2}-27)}{x} \\ \\ x^{2}-27 \\ \\ x^{2}=27 \\ \\ x_{1}=3\sqrt{3} \\ \\ x_{2}=-3\sqrt{3}$