Question

Найдите сумму и произведение корней квадратного уравнения: x²-10x+9=0

Answer 1

$x^{2} - 10x + 9 = 0 \\ d = 100 - 4 \times 9 = 64$

$x_{1} = \frac{10 + 8}{2} = 9$

$x_{2} = \frac{10 - 8}{2} = 1$

Answer 2

$x {}^{2} - 10x + 9 = 0$

$d = b {}^{2} - 4ac = 100 - 36 = 64$

$x = \frac{ - b + - \sqrt{d} }{2a} = \frac{10 + - 8}{2}$

$x = \frac{10 + 8}{2} = \frac{18}{2} = 9$

$x = \frac{10 - 8}{2} = \frac{2}{2} = 1$

$x + x = 9 + 1 = 10$

$x \times x = 9 \times 1 = 9$