Question

AJUDAAAA PLS x² - 5x + 8 = 0​

Answer 1

AJUDAAAA PLS x² - 5x + 8 = 0​

$x^2-5x+8=0\quad :\quad x=\frac{5}{2}+i\frac{\sqrt{7}}{2},\:x=\frac{5}{2}-i\frac{\sqrt{7}}{2}$

PASSOS

$x^2-5x+8=0\\x_{1,\:2}=\frac{-\left(-5\right)\pm \sqrt{\left(-5\right)^2-4\cdot \:1\cdot \:8}}{2\cdot \:1}\\x_{1,\:2}=\frac{-\left(-5\right)\pm \sqrt{7}i}{2\cdot \:1}\\x_1=\frac{-\left(-5\right)+\sqrt{7}i}{2\cdot \:1},\:x_2=\frac{-\left(-5\right)-\sqrt{7}i}{2\cdot \:1}\\x=\frac{5}{2}+i\frac{\sqrt{7}}{2},\:x=\frac{5}{2}-i\frac{\sqrt{7}}{2}$

Answer 2

Olá!

$\blue {{x}^{2} = - 5 x + 8 = 0}$

$\orange{\boxed {a = 1}}$

$\red{\boxed {b = -5}}$

$\purple{\boxed {c = 8}}$

$\sf {∆= {b}^{2} - 4.a.c}$

$\sf {∆= { - (5)}^{2} - 4.1.8}$

$\sf {∆= 25 - 32}$

$\sf{\green {∆= - 7}}$

Não iremos calcular as raízes, pois o resultado do discriminante deu negativo. Portanto, não existe raízes negativas.