Question

Помогите пожалуйста!!!​

Answer 1

a)

$2 {x}^{2} + 7x - 9 = 0 \\ D = {7}^{2} - 4 \times 2 \times ( - 9) = \\ 49 + 72 = 121 \\ x_{1} = \frac{ - 7 + 11}{2 \times 2} = \frac{4}{4} = 1 \\ x_{2} = \frac{ - 7 - 11}{2 \times 2} = - \frac{18}{4} = - 4.5$

б)

По теореме Виета:

${x}^{2} + bx + c = 0 \\ x _{1} + x_{2} = - b \\ x _{1} x_{2} = c$

${x}^{2} - 16x + 63 = 0 \\ x _{1} + x_{2} = 16\\ x _{1} x_{2} =63 \\ x_{1} = 9\\ x_{2} = 7$

Answer 2

Ответ:

$a) \: \: \: 2 {x}^{2} + 7x - 9 = 0 \\ 2 {x}^{2} - 2x + 9x - 9 = 0 \\ 2x(x - 1) + 9(x - 1) = 0 \\ (2x + 9)(x - 1) = 0 \\ x1 = - 4.5 \\ x2 = 1 \\ \\ b) \: \: \: {x}^{2} - 16x + 63 = 0 \\ {x}^{2} - 7x - 9x + 63 = 0 \\ x(x - 7) - 9(x - 7) = 0 \\ (x - 9)(x - 7) = 0 \\ x1 = 9 \\ x2 = 7$