Question

Розв’яжіть рівння за допомогою дискримінанта

Answer 1

1)

$- 2x + 10 = 0 \\ 2x = 10 \\ x = 10 \div 2 \\ x = 5$

2)

$4 {x }^{2} + 9x +5 = 0 \\ d = {9}^{2} - 4 \times 4 \times 5 = 81 - 80 = 1 \\ x_{1} = \frac{ - 9 + 1}{2 \times 4} = - \frac{8}{8} = - 1\\ x _{2} = \frac{ - 9 - 1}{4 \times 2} = - \frac{10}{8} = - \frac{5}{4 } = - 1.25$

3)

$9 {x}^{2} + 1 = 6x \\ 9 {x}^{2} - 6x + 1 = 0 \\ d = ( - 6) {}^{2} - 4\times 9 \times 1 = 36 - 36 = 0 \\ x = \frac{6}{9 \times 2 } = \frac{1}{3}$