Question

Determine as raízes ou zeros da função quadrática f(x) = x²– 2x – 3 *

a) -3 e 1

b) 3 e 1

c) 3 e -1

d) -3 e -1

Answer 1

$f(x) = x^2 - 2x - 3\\\\x = \frac{2 \pm \sqrt{2^2 - 4.(-3).1}}{2.1}\\x = \frac{2 \pm \sqrt{4 + 12}}{2}\\x = \frac{2 \pm \sqrt{16}}{2}\\x = \frac{2 \pm 4}{2}\\\\x_1 = \frac{2 + 4}{2} = \frac{6}{2} = 3\\x_2 = \frac{2 - 4}{2} = \frac{-2}{2} = -1$

Resposta: 3 e -1 (c)