Question

1- Resolva as equações do 2º grau. a) x² - 10x + 9 = 0 b) x² - 12x + 20 = 0 c)-2x² +11x-5=0​

Answer 1

a) x² - 10x + 9 = 0

a = 1

b = -10

c = 9

Δ = b² - 4ac

Δ = (-10)² - 4 × 1 × 9

Δ = 100 - 36

Δ = 64

$x = \frac{ - b \: ± \: \sqrt{Δ} }{2a}$

$x = \frac{10  ± 8 }{2}$

$x'= \frac{10 + 8}{2}$

$x' = \frac{18}{2} \\ x' = 9 \: \: \:$

$x'' = \frac{10 - 8}{2}$

$x'' = \frac{2}{2} \\ x'' = 1 \:$