Question

ME AJUDEM PORFAVOR TEM QUE FAZER IGUAL A LETRA “A”

Answer 1

a)

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

b)

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

c)

${x}^{2} - 5x - 6 = 0 \\ ∆= {( - 5)}^{2} - 4 \times 1 \times - 6 \\ ∆=25 + 24 = 49 \\ x1 = \frac{ - b + \sqrt{∆} }{2a} = \frac{ - ( - 5) +7}{2} = \frac{5 + 7}{2} = \frac{12}{2} = 6 \\ x2 = \frac{ - b - \sqrt{∆} }{2a} = \frac{ - ( - 5) - 7}{2} = \frac{5 - 7}{2} = \frac{ - 2}{2} = - 1$