Question

qual o resultado dessa equação de segundo grau completa ?

x² -3x -4 = 0

Answer 1

Explicação passo-a-passo:

$\sf x^2-3x-4=0$

$\sf \Delta=(-3)^2-4\cdot1\cdot(-4)$

$\sf \Delta=9+16$

$\sf \Delta=25$

$\sf x=\dfrac{-(-3)\pm\sqrt{25}}{2\cdot1}=\dfrac{3\pm5}{2}$

$\sf x'=\dfrac{3+5}{2}~\rightarrow~x'=\dfrac{8}{2}~\rightarrow~\red{x'=4}$

$\sf x"=\dfrac{3-5}{2}~\rightarrow~x"=\dfrac{-2}{2}~\rightarrow~\red{x"=-1}$