1. x² - 12x - 45 < 0
x² - 12x - 45 = 0
D = b² - 4ac = 12² + 4*45 = 144 + 180 = 324 = 18²>0
x1 = ![\frac{12 + 18}{2} = 15 \frac{12 + 18}{2} = 15](https://tex.z-dn.net/?f=%5Cfrac%7B12+%2B+18%7D%7B2%7D+%3D+15)
x2 = ![\frac{12 - 18}{2} = -3 \frac{12 - 18}{2} = -3](https://tex.z-dn.net/?f=%5Cfrac%7B12+-+18%7D%7B2%7D+%3D+-3)
Ответ: x∈(-3; 15)
2. (x+7)(x-5) > 0
x² - 5x + 7x - 35 > 0
x² + 2x - 35 > 0
x² + 2x - 35 = 0
D = b² - 4ac = 4 + 35 * 4 = 4 + 140 = 144 = 12²>0
x1 = ![\frac{-2+12}{2} = 5 \frac{-2+12}{2} = 5](https://tex.z-dn.net/?f=%5Cfrac%7B-2%2B12%7D%7B2%7D+%3D+5)
x2 = ![\frac{-2-12}{2} = -7 \frac{-2-12}{2} = -7](https://tex.z-dn.net/?f=%5Cfrac%7B-2-12%7D%7B2%7D+%3D+-7)
Ответ: x∈(-∞; -7) U (5; +∞)