Question

надо решить быстро через 10минут будет звонок!)
Дам 17балов

Answer 1

$1)x^{2} + 10x + 25 = 0 \\ (x + 5) ^{2} = 0 \\ x + 5 = 0 \\ x = - 5 \\ 2) {x}^{2} - 4x - 12 = 0 \\ {x}^{2} + 2x - 6x - 12 = 0 \\ x(x + 2) - 6(x + 2) = 0 \\ (x + 2)(x - 6) = 0 \\ x + 2 = 0 \\ x - 6 = 0 \\ x = - 2 \\ x = 6 \\ 3) {x}^{2} - 6x + 7 = 0 \\ {x}^{2} - 6x = - 7 \\ x {}^{2} - 6x + ( \frac{6}{2} {)}^{2} = - 7 + ( \frac{6}{2} {)}^{2} \\ x - ( \frac{6}{2} ) {}^{2} = 2 \\ (x - 3) {}^{2} = 2 \\ x = \sqrt{2} + 3 \\ x = - \sqrt{2} + 3 \\ 4)3x {}^{2} + 2x - 1 = 0 \\ 3 {x }^{2} + 3x - x - 1 = 0 \\ 3x(x + 1) - (x + 1) = 0 \\ (x + 1)(3x - 1) = 0 \\ x + 1 = 0 \\ 3x - 1 = 0 \\ x = - 1 \\ x = \frac{1}{3}$