Question

ПОЖАЛУЙСТА ПОМОГИТЕ СРОЧНО , нужно сдать утром

Answer 1

4)

${x}^{2} + bx + c = 0 \\ b = - (x _{1} + x _{2}) = - ( - 5 + 2) = \\ - ( - 3) = 3 \\ c =x _{1} \times x _{2} = - 5 \times 2 = - 10\\ {x}^{2} + 3x - 10 = 0$

5)

$5 {x}^{2} - 15x = 0 \\ x(x - 3) = 0 \\ x _{1} = 0 \\ x _{2} = 3$

$2x {}^{2} - 72 = 0 \\ {x}^{2} - 36 = 0 \\ (x - 6)(x + 6) = 0 \\ x _{1} = 6 \\ x _{2} = - 6$

$5 {x}^{2} + 10 0= \\ 5{x}^{2} = - 100 \\ {x}^{2} = - 20$

нет корней, т.к. каадрат люього числа не может быть отрицательным

6)

${x}^{2} - 9x + 8 = 0 \\ x _{1} + x _{2} = 9 \\ x _{1} \times x _{2} = 8 \\ x _{1} = 8 \\ x _{2} = 1$

$4 {x}^{2} - 5x - 6 = 0 \\ d = ( - 5) {}^{2} - 4 \times 4 \times ( - 6)= \\ 25 + 96 = 121 \\ x _{1} = \frac{5 + 11}{2 \times 4} = \frac{16}{8} = 2 \\ x _{2} = \frac{5 - 11}{2 \times 4} = - \frac{6}{8} = - \frac{3}{4} = - 0.75$

7)

х не равно 0

$\frac{x - 5}{ x } = \frac{4x + 1}{3x} \\ 3x(x - 5) = x(4x + 1) \\ 3 {x}^{2} - 15x = 4 {x}^{2} + x \\ 4 {x}^{2} - 3 {x}^{2} + x + 15x = 0 \\ {x}^{2} + 16x = 0 \\ x(x + 16) = 0 \\ x = - 16$