Question

No conjunto R (reais) a solução da equação x

2 − 8x + 12 = 0 é:

a) ∅ b) {−2, 6} c) {−6, 2} d) {2, 6} e) {0, 2}

Answer 1

Resposta:

2 e 6, alternativa D

Explicação passo a passo:

$x = \frac{-(-8)+-\sqrt{(-8)^{2}-4(1)(12)}}{2(1)}\\x = \frac{8+-\sqrt{64-48}}{2}\\\\x = \frac{8+-\sqrt{16}}{2}\\\\\\x = \frac{8+-4}{2}\\\\\\\\x = 12/2 = 6\\ou \\\\x = 4/2 = 2$

Answer 2

Resposta:

$\textsf{Leia abaixo}$

Explicação passo a passo:

$\mathsf{x^2 - 8x + 12 = 0}$

$\mathsf{\Delta = b^2 - 4.a.c}$

$\mathsf{\Delta = (-8)^2 - 4.1.12}$

$\mathsf{\Delta = 64 - 48}$

$\mathsf{\Delta = 16}$

$\mathsf{x = \dfrac{-b \pm \sqrt{\Delta}}{2a} = \dfrac{8 \pm \sqrt{16}}{2} \rightarrow \begin{cases}\mathsf{x' = \dfrac{8 + 4}{2} = \dfrac{12}{2} = 6}\\\\\mathsf{x'' = \dfrac{8 - 4}{2} = \dfrac{4}{2} = 2}\end{cases}}$

$\boxed{\boxed{\mathsf{S = \{6;2\}}}}\leftarrow\textsf{letra D}$