Question

4)As raízes da equação x .(x - 2) = 2.(x+6) são:
a) 2e3
b)0e6
c) 2e6
d)-2e6
e)2e-6
​

Answer 1

Resposta:

Item d

Explicação passo-a-passo:

$x(x-2)=2(x+6)\\\\x^{2}-2x=2x+12\\\\x^{2}-2x-2x-12=0\\\\x^{2}-4x-12=0\\\\\\\Delta=(-4)^{2}-4.1.(-12)=16+48=64\\ \\\\\\x=\dfrac{-(-4)\pm\sqrt{64}}{2.1}\\\\x=\dfrac{4\pm8}{2}\\\\x_1=\dfrac{4+8}{2}=\dfrac{12}{2}=6\\ \\x_2=\dfrac{4-8}{2}=\dfrac{-4}{2}=-2$

$\boxed{\boxed{D}}$

Answer 2

Resposta:

Explicação passo-a-passo:

x.(x - 2) = 2.(x+6)

x² - 2x = 2x + 6

x² -2x - 2x - 6 = 0

x² - 4x - 12 = 0

Pela formula de Bhascara ficará:

x = 4 ± √(-4)² - 4.1.(-12)/2.1

x = 4 ± 8/2

x = 6 e -2