Question

15. As raízes da equação x2 – X – 20 = 0
a) xy = -4 e xy = 5
b) x1 = 7 e x2 = 9
c) X1 = -25 e x2 = 75
d) x1 = -7 e X2=4
e) x1 = 6 e xy = 8

Answer 1

Resposta:

x² - x - 20 = 0

x² - 4x - 5x - 20 = 0

x ( x+4 ) - 5( x+4 ) = 0

( x+4 ) × ( x-5 ) = 0

x + 4 = 0

x = 0-4

x = -4

x - 5 = 0

x = 0+5

x = 5

x¹ = -4 | x² = 5