Очень срочно!!!! ........................

1. a² - b² = (a - b)(a + b); x² - 49 = (x - 7)(x + 7).
3. $\frac{x}{x - 2} : \frac{1}{ x^{2} - 4} = \frac{x}{x - 2} * \frac{ x^{2} - 4}{1} = \frac{x}{x - 2} * \frac{(x - 2)(x + 2)}{1} = x(x - 2) = x^{2} - 2x$
5. $\sqrt{a^{2} } = a; \sqrt{(x - 5)^{2} } = (x - 5)^{2} = x^{2} - 10x + 25$
6. x² - 10x = 0, x² + 10 = 0.
7. $ax^{2} + bx + c = 0 \\ D = b^{2} - 4ac \\ x_{1} = \frac{- b - \sqrt{ b^{2} - 4ac} }{2a} \\ x_{2} = \frac{-b + \sqrt{ b^{2} - 4ac} }{2a} \\ \\ 5 x^{2} - 3x - 2 = 0 \\ D = 9 + 4 * 5 * 2 = 49 \\ x_{1} = \frac{3 - 7}{10} = \frac{-4}{10} = - 0.4 \\ x_{2} = \frac{3 + 7}{10} = \frac{10}{10} = 1$