Resposta:
Letra c → ( -1 , 5 )
Explicação passo a passo:
f(x) = x² - 4x – 5
x² - 4x - 5 = 0
coeficientes
a = 1
b = -4
c = -5
Δ = b² -4ac
Δ = ( -4)² - 4(1)(-5)
Δ = 16 + 20
Δ = 36
[tex]x=\dfrac{-b\pm\sqrt{\Delta} }{2a}\\ \\ \\ x=\dfrac{-(-4)\pm\sqrt{36} }{2.(1)}=\dfrac{4\pm6}{2}\\ \\ \\ x'=\dfrac{4-6}{2}=-\dfrac{2}{2}=\boxed{-1}\\ \\ \\ x"=\dfrac{4+6}{2}=\boxed{5}[/tex]
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Resposta:
Letra c → ( -1 , 5 )
Explicação passo a passo:
f(x) = x² - 4x – 5
x² - 4x - 5 = 0
coeficientes
a = 1
b = -4
c = -5
Δ = b² -4ac
Δ = ( -4)² - 4(1)(-5)
Δ = 16 + 20
Δ = 36
[tex]x=\dfrac{-b\pm\sqrt{\Delta} }{2a}\\ \\ \\ x=\dfrac{-(-4)\pm\sqrt{36} }{2.(1)}=\dfrac{4\pm6}{2}\\ \\ \\ x'=\dfrac{4-6}{2}=-\dfrac{2}{2}=\boxed{-1}\\ \\ \\ x"=\dfrac{4+6}{2}=\boxed{5}[/tex]