Question

x²-4x-5=0 como faz???

Answer 1

x² - 4x - 5 = 0

Δ = (-4)² - 4(1)(-5)
Δ = 16 + 20 = 36
√Δ = 6

x' = (4 + 6)/2 = 10/2 = 5

x'' = (4 - 6)/2 = -2/2 = -1

Resposta: S={x ∈ R / x = -1 ou x = 5}

Espero ter ajudado.

Answer 2

Resposta:

$S=\{-1,5\}$

Explicação passo-a-passo:

$x^{2} -4x-5=0$

$a=1\\b=(-4)\\c=(-5)$

$\Delta=b^{2} -4ac\\\Delta=(-4)^{2}-4\times1\times(-5)\\\Delta=16+20\\\Delta=36$

$x=\frac{-b\pm\sqrt{\Delta} }{2a} \\\\x=\frac{-(-4)\pm\sqrt{36} }{2\times1} \\\\x=\frac{4\pm6 }{2}$

$x_{1} =\frac{4+6}{2} =\frac{10}{2} =5\\\\x_{2} =\frac{4-6}{2} =-\frac{2}{2} =-1$

$S=\{-1,5\}$