Question

Решите уравнение x квадрате плюс 3 икс равно 4​

Answer 1

${x}^{2} + 3x = 4 \\ {x}^{2} + 3x - 4 = 0 \\ {x}^{2} + 4x - x - 4 = 0 \\ x(x + 4) - (x + 4) = 0 \\ (x + 4)(x - 1) = 0 \\ x + 4 = 0 \\ x - 1 = 0 \\ x1 = - 4 \\ x2 = 1$

Answer 2

${x}^{2} + 3x = 4 \\ {x}^{2} + 3x - 4 = 0 \\ d = {b}^{2} - 4ac = \\ \: = 9 + 16 = 25 \\x_{1} = \frac{ - 3 + \sqrt{25}}{2} = \\ = \frac{ - 3 + 5}{2} = \frac{2}{2} = 1 \\ x_{2} = \frac{ - 3 - 5}{2} = \frac{ - 8}{2} = - 4 \: .$