Question

9-х^2>3х решите уравнение

Answer 1

скажи, а какой знак после х?

Answer 2

$9-x^2 > 3x\\- x^2 - 3x + 9 > 0\\x^2 + 3x - 9 < 0\\D = b^2 - 4ac = 3^2 + 4*9 = 9 + 36 = 45. D > 0.\\x_{1} = \frac{-3 + \sqrt{45}} {2} = \frac{-3 + 3\sqrt{5}} {2}  = \frac{3} {2}(\sqrt{5}-1)\\x_{2} = \frac{-3 - \sqrt{45}} {2} = \frac{-3 - 3\sqrt{5}} {2} = -\frac{3} {2}(\sqrt{5}+1)\\-\frac{3} {2}(\sqrt{5}+1) < x < \frac{3} {2}(\sqrt{5}-1)$