Question

Determine as raízes da equação
${x}^{2} - 4x - 5 = 0$
​

Answer 1

Resposta:

x' = 5 e x'' = -1

Explicação passo a passo:

x² - 4x - 5 = 0

a = 1

b = -4

c = -5

$\Delta = b^2 -4ac\\\\\Delta = (-4)^2-4*1*(-5)\\\\\Delta = 16 + 20\\\\\Delta = 36\\\\x' = \frac{-b+\sqrt{\Delta} }{2a} \\\\x'=\frac{-(-4)+\sqrt{36} }{2*1}\\\\x' = \frac{4+6 }{2} = \frac{10}{2} \\\\x' = 5\\\\\\x'' = \frac{-b-\sqrt{\Delta} }{2a} \\\\x''=\frac{-(-4)-\sqrt{36} }{2*1}\\\\x'' = \frac{4-6 }{2} = \frac{-2}{2} \\\\x'' = -1$