Question

calcule o valor de x.

Answer 1

x + 10 = 15
x = 15 - 10
x = 5

Answer 2

(15 + x) . 15 = [(x + 10) + 5]. (x + 10)


225 + 15x = [x + 15] . (x + 10)

15x + 225 = x^2 + 25x + 150


x^2 + 10x - 75

delta = b^2 - 4ac

d = 100 + 300 = 400

x = -b +- rz d / 2a

x = -10 +- 20 / 2 

x1 = (-10 + 20) / 2 = 5 (resposta!)

x2 = (-10 - 20) / 2 = -15 (descarta)