Question

quanto é a equação (x-2).(x+4)+x+1

Answer 1

$(x-2).(x+4)+x+1 = 0 \\ \\ x^2 + 2x - 8 +x +1 = 0 \\ \\ x^2 + 3x - 7 = 0$

Resolvendo por Bháskara.

$x = \dfrac{-b \pm \sqrt{b^2 -4*a*c}}{2*a}$

a=1, b=3, c=−7

Δ=b2−4ac
Δ=(3)2−4*(1)*(−7)
Δ=9+28
Δ=37

$x = \dfrac{-b \pm \sqrt{\triangle}}{2*a} \\ \\ \\ x = \dfrac{-3 \pm \sqrt{37}}{2*1} \\ \\ \\ x = \dfrac{-3 \pm \sqrt{37}}{2} \\ \\ \\ x' = \dfrac{-3 + \sqrt{37}}{2} \\ \\ \\ x'' = \dfrac{-3 + \sqrt{37}}{2}$

S = {$\dfrac{-3 + \sqrt{37}}{2}, \dfrac{-3 - \sqrt{37}}{2}$}