3. Докажите тождество: (x-3-x-3)* 7x-4x-4/9x-3x²=x-4 7x-42

$$ (\frac{x-3}{7x-4} - \frac{x-3}{x-4}) * \frac{7x-4}{9x-3x^2} = \frac{2}{x-4} $$ $$ \frac{(x-3)(x-4) - (x-3)(7x-4)}{(7x-4)(x-4)} * \frac{7x-4}{9x-3x^2} = \frac{2}{x-4} $$ $$ \frac{(x-3)((x-4) - (7x-4))}{(7x-4)(x-4)} * \frac{7x-4}{3x(3-x)} = \frac{2}{x-4} $$ $$ \frac{(x-3)(x-4 - 7x+4)}{(7x-4)(x-4)} * \frac{7x-4}{3x(3-x)} = \frac{2}{x-4} $$ $$ \frac{(x-3)(-6x)}{(7x-4)(x-4)} * \frac{7x-4}{3x(3-x)} = \frac{2}{x-4} $$ $$ \frac{-6x(x-3)}{3x(3-x)(x-4)} = \frac{2}{x-4} $$ $$ \frac{-2(x-3)}{(3-x)(x-4)} = \frac{2}{x-4} $$ $$ \frac{2(3-x)}{(3-x)(x-4)} = \frac{2}{x-4} $$ $$ \frac{2}{(x-4)} = \frac{2}{x-4} $$ Тождество доказано. Ответ: Тождество доказано