Question

Determine as raízes das equaçãoes abaixo a) x2-5x=0 b) -x2+12x=0 c)x2-9x=0 d) x2-4x-12=0

Answer 1

a)

x² - 5x = 0
x (x - 5) = 0

x1:

x = 0

x2:

x - 5 = 0
x = 5

b)

-x² + 12x = 0
x (-x + 12) = 0

x1:

x = 0

x2:

-x + 12 = 0
-x = -12
x = 12

c)

x² - 9x = 0
x (x - 9) = 0

x1:

x = 0

x2:

x - 9 = 0
x = 9

d)

x²-4x-12 = 0

Δ = b² - 4.a.c
Δ = 16 - 4.1(-12)
Δ = 64

x = -b +- √Δ / 2a
x = 4 +- 8 / 2

x1 = 4+8/2 = 6
x2 = 4-8/2 = -2