Resposta:
b) -1 e 5
Explicação passo-a-passo:
Usando a fórmula de Báskara:
[tex]x^{2} -4x-5=0\\a=1\\b= -4\\c=-5\\\\x =\frac{-b+\sqrt{b^{2} -4ac} }{2a} \\x =\frac{4+\sqrt{-4^{2} -4.1.(-5)} }{2.1} \\x =\frac{4+\sqrt{16 +20} }{2} \\x =\frac{4+\sqrt{36} }{2} \\x =\frac{4+6}{2}\\\\x_{1}= \frac{4+6}{2}=5\\x_{2}= \frac{4-6}{2}=-1[/tex]
