Question

Determine as raízes de (x-2)(x+5): 0

Answer 1

Vamos lá,

(x - 2) * (x + 5) = 0
x² + 5x - 2x - 10 = 0
x² + 3x - 10 = 0
Δ = 3² - 4 * 1 * (-10)
Δ = 9 + 40
Δ = 49

$x=\frac{-3\pm \sqrt{49}}{2\cdot 1}\to x=\frac{-3\pm 7}{2}\\ \\ x'=\frac{4}{2}\to x'=2\\ \\ x''=\frac{-10}{2}\to x''=-5\\ \\ \boxed{\boxed{S=\{2,-5\}}}$

Espero ter ajudado (:
Bons estudos!

Answer 2

(x - 2) . (x + 5) = 0
x² + 5x - 2x - 10 = 0
x² + 3x - 10 = 0

a = 1; b = 3; c = -10

x = [- b ± √(b² - 4ac)] / 2a
x = [- 3 ± √(3² - 4 . 1 . [-10])] / 2 . 1
x = [- 3 ± √(9 + 40)] / 2
x = [- 3 ± √49] / 2
x = [- 3 ± 7] / 2
x' = [- 3 + 7] / 2 = 4 / 2 = 2
x'' = [- 3 - 7] / 2 = -10 / 2 = -5

S = {-5, 2}

Espero ter ajudado. Valeu!