Question

determine os numeros -2,0,1,4 quais deles sao raizes da equacao.
X-2X-8=0

Answer 1

$x^{2}-2x-8=0,~onde: \\ \\ a=1,~b=-2,~c=-8 \\ \\ \Delta~=b^{2}-4.a.c \\ \Delta~=(-2)^{2}-4.1.(-8) \\ \Delta~=4+32 \\ \Delta~=36 \\ \\ x= \frac{-b\pm \sqrt{\Delta~}}{2.a}= \frac{2\pm \sqrt{36}}{2.1} \\ x= \frac{2\pm6}{2} \\ \\ x'= \frac{2+6}{2}= \frac{8}{2}=4 \\ x''= \frac{2-6}{2}= \frac{-4}{2}=-2$

As raízes dessa equação são -2 e 4.

Answer 2

Resolvendo a equação: 
a = 1, b  = -2, c = -8
Δ = b² - 4.a.c
Δ = (-2)² - 4.1.(-8)
Δ = 4 + 32
Δ = 36

x = (-b+/-√Δ)/2a
x = [-(-2)+/-√36]/2.1
x = (2+/-6)/2
x' = 8/2 --> x' = 4
x" = -4/2 --> x" = -2
raízes: (-2 e 4)