Question

Resolva as equações:

a) x² -7x + 12 =0
b) x² -49 =0
c) x² -10x =0
d) -x² 15x -4 =0

Answer 1

a)

x² - 7x + 12 = 0

Δ = b² - 4.a.c

Δ = -7² - 4 . 1 . 12

Δ = 49 - 4. 1 . 12

Δ = 1

Há 2 raízes reais.

x = (-b +- √Δ)/2a

x' = (--7 + √1)/2.1

x'' = (--7 - √1)/2.1

x' = 8 / 2

x'' = 6 / 2

x' = 4

x'' = 3

b)

x² - 49 = 0

x² = 49

x = + ou - √49

x' = 7

x'' = -7

c)

x² - 10x = 0

Δ = b² - 4.a.c

Δ = -10² - 4 . 1 . 0

Δ = 100 - 4. 1 . 0

Δ = 100

Há 2 raízes reais.

x = (-b +- √Δ)/2a

x' = (--10 + √100)/2.1

x'' = (--10 - √100)/2.1

x' = 20 / 2

x'' = 0 / 2

x' = 10

x'' = 0