Question

помогите пожалуйста!!!!((​

Answer 1

Ответ:

$1)2x {}^{2} - 18 = 0 \\ x - 9 = 0 \\ x {}^{2} = 9 \\ x1 = 3 \\ x2 = - 3$

$2)3x {}^{2} + 5x = 0 \\ x(3x + 5) = 0 \\ x1 = 0 \\ x2 = - \frac{5}{3}$

$3)x {}^{2} - 5x + 6 = 0 \\ x1 = 2 \\ x2 = 3$

$4)2x {}^{2} + x + 8 = 0 \\ a = 2.b = 1.c = 8 \\ d = 1 - 4 \times 2 \times 8 = - 65$

нет корней

$7x { }^{2} + 6x - 1 = 0 \\ x1 = - 1 \\ x2 = \frac{1}{7}$

$6) \frac{5}{x - 3} - \frac{8}{x} = 3 \\ \frac{5x - 8(x - 3) - 3x(x - 3)}{x(x - 3)} = 0 \\ \frac{6x + 24 - 3x {}^{2} }{x(x - 3)} = 0 \\ 6x + 24 - x {}^{2} = 0 \\ x {}^{2} - 2x - 8 = 0 \\ x1 = - 2 \\ x2 = 4$