Question

(х-4) (х+5) - (х+6) = -х​

Answer 1

Ответ:

$(x - 4)(x + 5) - (x + 6) = - x \\ {x}^{2} + 5x - 4x - 20 - x - 6 = - x \\ {x}^{2} - 26 + x = 0 \\ {x}^{2} + x - 26 = 0 \\ d = {b}^{2} - 4ac = {1}^{2} - 4 \times 1 \times ( - 26) = 1 + 104 = 105 \\ x1 = \frac{ - b - \sqrt{d} }{2a} = \frac{ - 1 - \sqrt{105} }{2} \\ x2 = \frac{ - b + \sqrt{d} }{2a} = \frac{ - 1 + \sqrt{105} }{2}$