Question

X ao quadrado menos 4 x menos 5

Answer 1

${x}^{2} - 4x - 5 = 0 \\ a = 1 \\ b = - 4 \\ c = - 5 \\ x = \frac{ - b + - \sqrt{ {b}^{2} - 4 \times a \times c} }{2 \times a} \\ x = \frac{ - ( - 4) + - \sqrt{ {( - 4)}^{2} - 4 \times 1 \times ( - 5) } }{2 \times 1} \\ x = \frac{4 + - \sqrt{16 + 20} }{2} \\ x = \frac{4 + - \sqrt{36} }{2} \\ x = \frac{4 + - 6}{2} \\ x1 = \frac{4 + 6}{2} = \frac{10}{2} = 5 \\ x2 = \frac{4 - 6}{2} = \frac{ - 2}{2} = - 1$