Question

qual a resposta por favor ?x²-3x-4=0

Answer 1

Olá !


Resolução :


X² - 3X - 4 = 0


A = 1 ; B = -3 ; C = -4


∆ = b² - 4 • a • c

∆ = (-3)² - 4 • 1 • (-4)

∆ = 9 + 16

∆ = 25

X = -b ± √∆ / 2a

X = -(-3) ± √25 / 2 • 1

X = 3 ± 5 / 2

X' = 3 + 5 / 2 = 8/2 = 4

X'' = 3 - 5 / 2 = -2/2 = -1


Resposta :


S = { -1 , 4 }

Answer 2

Resposta:

S = {- 1, 4}

Explicação passo-a-passo:

$x^{2} -3x-4=0$

$a=1\\b=(-3)\\c=(-4)$

$\Delta=b^{2} -4ac\\\Delta=(-3)^{2} -4\times1\times(-4)\\\Delta=9+16\\\Delta=25$

$x=\frac{-b\pm\sqrt{\Delta} }{2a} \\\\x=\frac{-(-3)\pm\sqrt{25} }{2\times1} \\\\x=\frac{3\pm5}{2}$

$x_{1} =\frac{3+5}{2} =\frac{8}{2} =4\\\\x_{2} =\frac{3-5}{2} =-\frac{2}{2} =-1$