Question

4) A soma entre as raízes da equação 2x² + 4x - 6 = 0 é igual a:
a) -1 b) -2 d) 1 e) 2​

Answer 1

Resposta:

$2x^2+4x-6=0$

Resolvendo por Bhaskara:

$a=2\\b=4\\c=-6$

$\Delta=b^2-4ac\\\Delta=4^2-4\cdot2\cdot(-6)\\\Delta=16+48\\\Delta=64$

$x=\dfrac{-4\pm\sqrt\Delta}{2a}\\\\x=\dfrac{-4\pm\sqrt{64}}{2\cdot2}\\\\x=\dfrac{-4\pm8}{4}\\\\x_1=\dfrac{-4+8}{4}=\dfrac{4}{4}=1\\\\x_2=\dfrac{-4-8}{4}=\dfrac{-12}{4}=-3$

Então, a soma das raízes é dada por:

$1+(-3)=-2$

Alternativa B.

Answer 2

Resposta:

a) 2

b) 4

c) -6

x= -b ±√b²-4.a.c /2 . a

x= -4±√4²- 4 . 2 . (-6) / 2 . 2

x=-4±√16 + 48 / 4

x= -4 ± √64 / 4

x= -4 ± 8 / 4

x'= -4+8/4    4/4  = 1

x"=-4 -8/4   -12/4  = -3

x' + x" = 1 - 3

= - 2

resposta correta letra b