Question

Щнайдіть корені рівняння

Answer 1

$5 {x}^{2} = 25x \\ {5x}^{2} - 25x = 0 \\ 5x(x - 5) = 0 \\ 5x = 0 \: \: \: \: \: x = 0 \\ x - 5 = 0 \: \: \: \: \: x = 5$

${100x}^{2} - 16 = 0 \\ {100x}^{2} = 16 \\ {x}^{2} = \frac{16}{100} \\ x = \sqrt{ \frac{16}{100} } = \frac{4}{10} = 0.4$

${3x}^{2} - 11x - 4 =0 \\ D = {( - 11)}^{2} - 4 \times 3 \times ( - 4) = 121 + 48 = 169 \\ x1x2 = \frac{ - ( - 11)±13}{2 \times 3} = \frac{11±13}{6} = - \frac{1}{3} \: ; \: 4$

${x}^{2} - 2x + 1 = 0 \\ x1 + x2 = 2 \\ x1 \times x2 = 1 \\ x = 1$

${2x}^{2} + 5x + 9 = x + 2 \\ {2x}^{2} + 5x - x + 9 - 2 = 0 \\ {2x}^{2} + 4x + 7 = 0 \\ D = {4}^{2} - 4 \times 2 \times 7 = 16 - 56 = - 40 \\ x = ∅$