Question

coloque na forma geral: (bhaskara )
x (x - 3 ) -40 =0

Answer 1

x . (x - 3) - 40 = 0
x² - 3x - 40 = 0

a = 1
b = -3
c = -40

Δ = b² - 4 .a . c
Δ  = (-3)² - 4 . 1 . (-40)
Δ = 9 + 160
Δ = 169

$\mathtt{\dfrac{-b+-~\sqrt{\Delta}}{2~.~a}~~=~~\dfrac{-(-3)+-~\sqrt{169}}{2~.~1}~~=~~\dfrac{3+-~13}{2}} \\ \\ \\ \mathtt{x' = \dfrac{3 + 13}{2}~~=~~\dfrac{16}{2}~~=~~\boxed8} \\ \\ \\ \mathtt{x'' = \dfrac{3 - 13}{2}~~=~~-\dfrac{10}{2}~~=~~\boxed{-5}}$

Resposta: S{ -5  e 8}