Question

resolva as equações abaixo:

Answer 1

a) 

$\frac{ x^{2}}{4} - \frac{x+4}{10} = 8$

Tirando o MMC de 4 e 10, temos: 

$\frac{5 x^{2} }{20} - \frac{2.(x+4)}{20} = \frac{160}{20}$

5x² - 2.(x + 4) = 160
5x² - 2x - 8 = 160
5x² - 2x - 8 -160 = 0
5x² - 2x - 168 = 0
Δ = b² - 4.a.c
Δ = (-2)² - 4 . 5 . -168
Δ = 4 + 3360
Δ = 3364

x = (-b +-√Δ)/2a
x = (2 +-58)/10
x1 = 2 + 58/10 → x1 = 60/10 → x1 = 6
x2 = 2 -58/10 → x2 = -56/10 → x2 = -28/5

b) -2x² + 800 = 0
-2x² = -800
2x² = 800
x² = 800/2
x² = 400
x = +-√400
x = +- 20